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Blood Pressure, 2012; 21: 45–57

ORIGINAL ARTICLE

Association between habitual sleep duration and blood pressure and
clinical implications: A systematic review

ELIZABETH DEAN1, ANDREA BLOOM2, MARGHERITA CIRILLO2, QUAN HONG2,
BRADLEY JAWL2, JEFFREY JUKES2, MANU NIJJAR2, SANJIN SADOVICH2 &
SELMA SOUSA BRUNO3
1Department

of Physical Therapy, Faculty of Medicine, University of British Columbia, Canada, 2Department of
Physical Therapy, Faculty of Medicine, University of British Columbia, Canada and 3Department of Physical Therapy,
Science Health Center, Federal University of Rio Grande of Norte, Natal, Brazil

Abstract
Elucidation of the association between short sleep duration and elevated blood pressure has implications for assessing and
managing hypertension in adults. Objective. To assess the relationship between sleep duration and blood pressure, and its role
in the etiology of hypertension. Methods. On a systematic search from MEDLINE, EMBASE, CINAHL, PEDro, PsychINFO
and grey literature were included articles with participants over 18 years, reported sleep duration, measured blood pressure or
diagnosed hypertension, and the relationship between sleep duration and blood pressure was analyzed. Results. Of 2522 articles
initially identified, 11 studies met the inclusion criteria. Sample sizes ranged from 505 to 8860 (aged  20–98 years). Five studies (aged  58–60 years) determined that sleep duration and blood pressure were unrelated. In younger adults, five studies
reported an association between short sleep duration and hypertension before adjustment for confounding variables; only
the findings from one study remained significant after adjustment. Two studies supported a sex association; women who sleep
less than 5–6 h nightly are at greater risk of developing hypertension. Conclusion. Sleep duration and blood pressure are
associated in both women and adults under 60 years. Controlled studies are needed to elucidate confounding factors and
the degree to which sleep profiles could augment diagnosis of hypertension and sleep recommendations to prevent or manage
hypertension.
Key Words: blood pressure, hypertension, sleep, sleep quality

Introduction
High blood pressure, estimated to cause 7.1 million
deaths worldwide annually (1), is a risk factor for ischemic heart disease, cerebrovascular disease, and cardiac
and renal failure (2). Over a quarter of the world’s adult
population was estimated to have hypertension in 2000;
this proportion is predicted to rise to 29% by 2025 (3).
In Canada, the 6-month healthcare cost for a single
patient with hypertension exceeds $3000, with drugs
accounting for more than 50% of the direct cost (4).
Although the need to integrate health promotion
and disease prevention strategies into biomedical care
is becoming better acknowledged in healthcare, some
authorities argue that a substantial gap persists between
knowledge and action (5). In line with this trend,
lifestyle factors and their modification are being

considered in preventing and managing hypertension
(2); however, these are unlikely to be maximally
exploited until the body of evidence supporting them
is firmly established. Given the economic and social
burdens associated with hypertension, the elucidation of the role of modifiable lifestyle risk factors in
prevalent conditions such as hypertension is justified
and highly compelling in terms of augmenting our
knowledge about effective, low risk, economical
approaches to its prevention and management.
The relationship between sleep and health has
become an increasing focus of scientific investigation
in part because of the impact of social factors on sleep
patterns. Artificial lighting and changes in stress and
social demands, for example, have contributed to
changes in sleep patterns over time (6); the average

Correspondence: Selma Sousa Bruno, Department of Physical Therapy, Science Health Center, Federal University of Rio Grande of Norte, Natal, Brazil,
and Visiting Professor, Department of Physical Therapy, Faculty of Medicine, University of British Columbia, Canada. Tel:  55 (84) 3342 2000. Fax: (84)
3342 2001. E-mail: [email protected]
(Received 13 March 2011; accepted 16 May 2011)
ISSN 0803-7051 print/ISSN 1651-1999 online © 2012 Scandinavian Foundation for Cardiovascular Research
DOI: 10.3109/08037051.2011.596320

46

E. Dean et al.

American sleeps 6.7 h a night (7). Although the optimal amount of sleep that people need has been debated
(6), a growing body of evidence supports the key role
of sleep in overall health and wellbeing. Conversely,
suboptimal sleep has been associated with a myriad of
health issues including coronary heart disease (8),
immune dysfunction (9), type II diabetes (10,11),
obesity (12) and mood disorders (13).
Short-term sleep deprivation studies support that
reduced habitual sleep increases blood pressure
(14,15). Related to this body of evidence are the
results of several population-based studies that conclude sleep apnea is an independent risk factor for
hypertension (16,17), and a causal link has been proposed (18). This relationship remains to be firmly
established for the general population. If such a relationship exists, sleep prescription and sleep hygiene
counseling could be adopted as a practical, nonpharmaceutical and economical intervention to prevent or mitigate hypertension as well as promote
general health and wellbeing.
The primary purpose of this study was to conduct
a literature review to evaluate systematically the evidence
associating habitual sleep duration with blood pressure
in adults. If a firm association exists, our secondary purpose was to establish whether a direct relationship exists
between habitual short sleep duration and hypertension.
Methods
Search strategy
We performed a systematic search of MEDLINE
(1950 to present), EMBASE (1980 to present),

CINAHL (1982 to present), PEDro, PsychINFO
(1800 to present), and grey literature (ProQuest, Networked Digital Library of Theses and Dissertations,
clinicaltrials.gov, Papers First). Initial searching was
conducted in November 2009 with a final search in
February 2010. The search strategies used MeSH
headings and keywords for “hypertension” or “blood
pressure” and “sleep”. In EMBASE and MEDLINE,
these results were filtered with keywords for sleep
duration: “duration*”, “quantit*”, “hour*”, or
“amount*”. The searches were limited to the English
language and adults (18 or 19, depending on the
database). Studies of children were excluded from the
analysis given their sleep requirements vary across
developmental stages (19). Relevant articles were
searched on Web of Science (1900 to present) to find
more recent literature citing these articles. A total of
2522 articles were identified for screening (Figure 1).
Inclusion and exclusion criteria
Studies were included if they (1) involved adult participants over 18 years or included separate analysis
of those 18 years and older, vs those below this age;
(2) reported participants’ habitual sleep duration; (3)
measured blood pressure, or recorded a diagnosis of
hypertension or use of antihypertensive medication;
and (4) analyzed the relationship between habitual
sleep duration and blood pressure.
Studies were excluded if they (1) exclusively
analyzed populations with diagnosed sleep disorders,
sleep disordered breathing, metabolic disease or
cardiovascular disease; (2) were not available in full
text; or (3) were not available in English.

Titles and abstracts
yielded by search
strategies
(n = 2522)
Articles excluded because neither title nor abstract was
relevant for review (n = 2497)

Duplicates removed (n = 6)

Full-text articles
reviewed (n = 19)
Articles excluded for not meeting inclusion criteria (n = 8):
Analyzed population with sleep-disordered breathing (n = 1)
Did not include participants’ habitual sleep duration (n = 2)
Did not analyze relationship between sleep and blood
pressure (n = 4)
Did not provide data or methods (n = 1)
Publications included
for systematic review
(n = 11)

Figure 1. Study selection flow chart.

Sleep duration and blood pressure
Data extraction and quality assessment
All initial search results were screened independently
by two reviewers for potentially relevant articles; irrelevant articles and duplicates were excluded. Full-text
review was then conducted on the resulting 19 studies
with respect to the specific inclusion and exclusion
criteria. Each article was reviewed independently by
the two reviewers who used a customized screening
tool. The reviewers aimed for consensus for study
selection; however, in the event of uncertainty or disagreement, a third person reviewed the article and
discussed his or her assessment with the reviewers.
Methodological quality was assessed using the
Downs and Black Quality Index (20). This index has
been reported to be valid and reliable, and allows for
assessment of both randomized and non-randomized
studies. In an evaluation of this quality assessment tool
(21), it scored high for internal consistency, test–
retest, inter-rater reliability, criterion validity and
respondent burden. The Downs and Black Quality
Index is based on 27 items within five categories:
study quality/reporting (10 items); external validity
(three items); internal validity – bias (seven items);
internal validity – confounding/selection bias (six
items); and power (one item). The highest achievable
score on the Downs and Black Quality Index is 32;
however, when it is applied to non-randomized studies, the maximum score is reduced to 19 (20). Each
review extracted independently date from articles and
summarized as study, country, study size, study design,
subject age, quantity of sleep and main findings.

Results
Study selection
A flow chart of the study search and selection process
appears in Figure 1. Our initial search strategy yielded
2522 articles from six resources: 990 from MEDLINE; 1038 from EMBASE; 141 from CINAHL; 138
from PsycINFO; 212 from grey literature sources; and
three from the Web of Science. After our stringent
selection process, 11 source studies resulted.

47

Table I. Quality assessment scores based on the Downs and Black
Quality Index of the source studies.

Study

Study External Internal Total
quality validity validity score
Year (/11)
(/3)
(/13) (/32)

Bjorvatn et al. (23)
Cappuccio et al. (30)
Choi et al. (24)
Gangwisch et al. (29)
Hall et al. (25)
Kawada et al. (26)
Knutson et al. (31)
Lima-Costa et al. (22)
Lopez-Garcia et al. (32)
Stranges et al. (27)
Van den Berg et al. (28)

2006
2007
2008
2006
2008
2008
2009
2008
2009
2008
2007

8
9
9
9
9
7
9
7
9
8
9

0
0
2
2
2
0
2
2
2
1
2

5
8
5
8
5
4
8
3
8
7
5

13
17
16
19
16
11
19
12
19
16
16

Each paper was given a score of 0/5 on the power sub-scale.

This review incorporates data from multiple countries, included both sexes (except one study) and most
had large sample sizes (Table II).
Measurement of habitual sleep and blood pressure
Table III compares studies with respect to measurement of habitual sleep and blood pressure measurement. All 11 source studies collected data on sleep
quantity from self-report through means of interview
or questionnaire. Two studies used wrist actigraphy
in addition to self-report to measure sleep (28,31).
Studies were inconsistent regarding attention to the
time of day for blood pressure measurement.
There were also marked inconsistencies across
studies regarding the qualifications and experience of
personnel taking blood pressure, the body position
and resting state of the subjects prior to taking blood
pressure, arm the blood pressure was taken, and
whether blood pressures were averaged (Table III).
Table III also shows detailed information on the
blood pressure and sleep data as well as hypertension
definitions. Hypertension was defined inconsistently
across the source studies.
Main findings

Participants and study design

There was marked variability among the source studies in how they represented and reported their results
(Table IV). Studies generally compared sleep duration
with a reference group whose nightly sleep was
approximately 7 h, though the exact parameters
varied. Most studies adjusted their findings for multiple confounding variables. The significance of the
relationship between sleep duration and blood pressure often changed with adjustments suggesting a role
for mediating variables.

Several types of study designs were reflected in the
source studies, and were mostly limited to older
adults (Table I). Therefore, our results reflect associations between habitual sleep duration and blood
pressure across the adult lifespan.

Age-related findings. Several studies exclusively analyzed older adults (22,28,32). Each of these studies
concluded that sleep duration is not associated with
prevalent hypertension in this population before or

Quality assessment
For the source studies, quality assessment scores derived
from the Downs and Black Quality Index appear in
Table I. The average score across all 11 studies is
15.82  2.79.

48

E. Dean et al.

Table II. Description of the samples of the source studies.
First author

Year

Bjorvatn
et al. (23)

2007

Cappuccio
et al. (30)

2007

Country

Study design

Study size

Subject age

Population source

Norway

Cross-sectional

8860

40–45

UK

Cross-sectional

5766; Men: 4199;
Women: 1567

Longitudinal
(mean 5-year
follow-up)
Cross-sectional

3691; Men: 2686;
Women: 1005

Hordaland Health Study data
(population-based, all born in
Hordaland county 1953–1957)
Whitehall II Study, white British civil
servants; Excluded: ethnic groups other
than white (n  612)
Normotensive population from cross-sectional
study

35–55

4222

20

Longitudinal
(8–10-year
follow-up)

4810

25–74

USA

Cross-sectional

1214

30–54

2008

Japan

Cross-sectional

4941

36–60

2009

USA

Cross-sectional

578

33–45

Choi et al.
(24)

2008

Korea

Gangwisch
et al. (29)

2006

USA

Hall et al.
(25)

2008

Kawada
et al. (26)

Knutson
et al. (31)

Longitudinal
(5-year
follow-up)

505 (535
for incident
hyper-tension
analysis)
1423

Lima-Costa
et al. (22)

2008

Brazil

Cross-sectional

Lopez-Garcia
et al. (32)

2009

Spain

Cross-sectional

3686

Longitudinal
(2-year
follow-up)
Comparative
cross-sectional

890

Stranges
et al. (27)

2008

UK; USA

van den Berg
et al. (28)

2007

Netherlands

Cross-sectional

UK: 6472; USA:
3027

5058

60–95

60

UK: 45–69;
USA: 35–79

58–98

Portion of Korean National Health and
Nutrition Survey (nationally
representative survey); Excluded: those
on medications for metabolic syndrome,
missing data on sleep or fasting time,
not enough time fasting
National Health and Nutrition
Examination Survey (civilian,
non-institutionalized US citizens);
Excluded: those with diagnosed
hypertension or blood pressure 140/90
mmHg at baseline
University of Pittsburgh’s Adult Health
and Behavior (AHAB) registry
(Southwestern Pennsylvania, principally
Allegheny county); Excluded: those with
atherosclerosis, chronic kidney or liver
disease, neurological disorder,
schizophrenia or psychotic illness,
pregnancy and the use of insulin,
glucocorticoid, antiarrhythmic,
psychotropic or weight-loss medications
Male employees of an electronics
company; Excluded: past medical
history of hypertension, dyslipidemia,
and/or diabetes mellitus
Chicago participants of CARDIA
(Coronary Artery Risk Development in
Young Adults) Study, white and African
American sub-populations; Excluded:
pregnant women, those missing
actigraphy data, taking antihypertensive
medications at baseline, or missing a
measure of DBP at baseline or
follow-up
Excluded: as above  those on
antihypertensive medications at
follow-up
Bambui Health Aging Study (communitybased cohort in Bambui city; 81.7% of
population 60 years old)
Population-based cohort representative of
non-institutionalized Spanish population
60 years old
Normotensive population from crosssectional study
Whitehall II Study (white British civil
servants); Western NY Health Study
(Erie or Niagara County, NY; white
population subset); Excluded:
incomplete data, ethnic groups other
than white
Rotterdam Study (population-based
cohort study, all 55 in district of
Rotterdam invited to participate)

Sleep duration and blood pressure

49

Table III. Measurement of sleep and blood pressure variables.

Study

BP measurement technique

Bjorvatn
et al. (23)

1. Relaxed sitting position
following 2 min rest; 2.
Three automated BP
measurements; 3. No
talking during
measurements

Cappuccio
et al. (30)

1. Three BP measures using
standard mercury
manometer; 2. Onset of
1st and 5th Korotkoff
sounds used to represent
SBP and DBP
1. In seated position
following 10 min rest; 2.
Two SBP and 2 DBP
measurements with a 5
min interval between
readings
1. Three BP measurements
taken at the same sitting;
2. No reading taken if
maximum cuff inflation
160 mmHg

Choi et al.
(24)

Gangwisch
et al. (29)

Specific question
posed and/or
technique used to
analyze sleep data

Definition of htn or
high BP

Method of sleep
data collection

Averaged final 2 of
3 readings

Defined high BP as
SBP 140 mmHg
or DPB 90
mmHg

Self-report
via selfadministered
questionnaire

Averaged final 2 of
3 readings

Defined htn as SBP/
DBP  140/90
mmHg, or regular use
of antihypertensive
medication

Self-report
questionnaire

Average of 2
readings

Defined htn as SBP or
DBP  130/85
mmHg

Self-report
questionnaire

N/A

Measured 3 times

Defined htn as
SBP  140 mmHg
or DPB  90 mmHg,
or self-report of
physician diagnosis,
hospital record, or
reported cause of
death
Defined high BP as
SBP  130 mmHg,
or DBP  85 mmHg,
or use of
antihypertensive
medication

Self-report
questionnaire

“How many
hours of sleep
do you usually
get a night (or
when you
usually sleep)?”

Self-report
through
in-person
interview
conducted
by trained
interviewers

Hours per night
slept over the
past 7 days;
asked separately
about sleep
duration on
weeknights
(SundayThursday) and
weekend nights
(Friday,
Saturday);
Weekly average
reported sleep
duration
calculated as the
weighted average
of weeknight and
weekend values
N/A

Calculation of BP

Hall et al.
(25)

1. Two measurements taken
consecutively on morning
after a 12-h fast; 2. BP
measured in a seated
position following 10 min
rest; 3. Mercury
sphygmomanometer used
on right arm

Average of 2
readings

Kawada
et al. (26)

1. Right arm in seated
position after 5 min rest;
2. Used oscillometric
sphygmomanometer; 3.
1st and 5th Korotkoff
sounds to indicate SBP
and DBP, respectively

1. If initial reading
was under
130/85 mmHg,
then BP was not
re-measured; 2.
Measured twice
after 3 min
interval if initial
reading  130/85
mmHg; lowest
reading retained

Defined high BP as
SBP  130 mmHg
and/or  85 mmHg

Self-report

Sleep duration
calculated as
total time in bed
(from bedtime to
rise time) minus
self-reported
sleep latency;
Calculated sleep
during workweek
and during free
time
independently
“How many
hours of sleep
do you have on
an average
week night?”

(Continued)

50

E. Dean et al.

Table III. (Continued).

Definition of htn or
high BP

Method of sleep
data collection

Averaged final 2 of
3 readings

Defined htn as SBP
140 mmHg, or
DPB 90 mmHg,
or use of
antihypertensive
medication

Self-report
during
clinical exam
and wrist
actigraphy
monitor

N/A

Average of 2 out of
3 readings

Defined htn as SBP
140 mmHg, or
DBP 90 mmHg,
or use of
antihypertensive
medication

Self-report

LopezGarcia
et al. (32)

1. Measured 6 times at
level of heart in right arm
at 2 min intervals; 2.
Measured after 5 min
rest in seated position
using mercury
sphygmomanometer

Average of 6
readings

Defined htn as SBP
140 mmHg, or
DBP 90 mmHg,
or use of
antihypertensive
medication, or
self-reported
physician diagnosis

Stranges
et al. (27)

1. Sitting position using
mercury
sphygmomanometer; 2.
1st and 5th Korotkoff
sounds used for SBP and
DBP, respectively

Averaged final 2 of
3 readings

Defined htn as SBP/
DBP  140/90
mmHg, or regular
use of
antihypertensive
medication

1. Self-report
through
home based
personal
interview
at baseline;
2. Phone
interview at
follow-up
Self-report
questionnaire

Study

BP measurement technique

Calculation of BP

Knutson
et al. (31)

1. Readings taken three
times after 5 min rest; 2.
Used Hawksley
random-0
sphygmomanometer and
digital BP monitor which
were calibrated against
each other for
consistency

Lima-Costa
et al. (22)

Specific question
posed and/or
technique used to
analyze sleep data
1. Actigraphy for
three
consecutive days
on 2 occasions
approximately
1 year apart; 2.
Self-reported
questions about
sleep duration
and quality
during clinical
exam
1. “During the
last month, in
the workdays
and without
considering the
weekends, at
what time did
you: lay down
to sleep; get
asleep; wake up;
leave the bed?”;
2. Weekend
sleeping habits
determined by
use of similar
question to
above; 3. Usual
sleep duration
determined by
formula
“How many hours
do you usually
sleep per day
(including sleep
at night and
during the
day)?”

Analyzed data from
two sources where
the following
questions were
posed: 1.
Whitehall II
study: “How
many hours of
sleep do you have
on an average
weeknight?”; 2.
Western NY
study: “On the
average, how
many hours did
you sleep each
night during the
last 5 weekday
nights (Sunday–
Thursday)?”
(Continued)

Sleep duration and blood pressure

51

Table III. (Continued).

Study

BP measurement technique

van den Berg
et al. (28)

1. Two blood pressure
measurements in sitting
at right brachial artery
with random-0
sphygmomanometer

Calculation of BP
Average of 2
readings

Definition of htn or
high BP
Defined htn as
SBP  160 mmHg, or
DBP  100 mmHg,
or current use of
antihypertensive
medication

Method of sleep
data collection
Self-report by
way of
in-person
home
interview,
and wrist
actigraphy

Specific question
posed and/or
technique used to
analyze sleep data
1. “During the
past month, how
many hours of
actual sleep did
you get at
night?”; 2. Wrist
actigraphy over
5–7 consecutive
nights;
actigraphy
algorithm used
on raw data

BP, blood pressure; SBP, systolic blood pressure; DBP, diastolic blood pressure.

after adjustment for confounding variables (Table IV).
Two studies analyzed age groups separately and provided data for those over 60 years of age (24,29). One
reported no association between sleep duration and
elevated blood pressure for subjects over 60 years of
age (24). The other study reported an increased likelihood of hypertension in older adults (60–85 years of
age), sleeping 9 h or more (hazard ratio (HR): 1.54;
95% confidence interval, CI 1.03–2.30) (29). This
relationship was no longer significant, however, when
the model was adjusted for daytime sleepiness, depression, physical activity, alcohol and salt consumption, smoking, pulse rate and gender (29).
One study reported that the risk of being diagnosed
with hypertension was twice as high in subjects under
60 years of age who slept 5 or fewer hours nightly
(HR  2.10; 95% CI 1.58–2.79) (29). Adjusting for
variables modestly attenuated this relationship but it
remained significant for subjects between 32 and 59
years of age who slept 5 or fewer hours nightly
(HR  1.60; 95% CI 1.19–2.14). In an unadjusted
analysis, another study reported that the prevalence of
elevated blood pressure was significantly higher
(p  0.009) with sleep duration 5 h for subjects
between 20 and 59 years of age (24). In a study of
adults between 33 and 45 years of age, short sleep duration was associated with higher blood pressure when
adjusted for age, sex and race (31). In a fully adjusted
model, the association was no longer significant. At a
5-year follow-up, short sleep duration was associated
with incident hypertension and each hour of sleep
reduction increased the odds by 37%. Similarly, the
relationship was attenuated with full adjustment. Interestingly, a significant association with changes in diastolic blood pressure remained ( p  0.03).
In an unadjusted analysis for a population
between 40 and 45 years of age, sleep duration of 5
h was positively related to blood pressure (23). After
full adjustment, however, sleep durations of 5–5.99 h
and 6–6.99 h became negatively associated with
systolic blood pressure.

One study reported no relationship between short
sleep (6 h vs 7–8 h) and elevated blood pressure in
participants who were between 30 and 54 years of age
(25). Another study compared 6 h with 6 h for
men 36–60 years of age and reported no significant
difference with respect to exhibiting higher blood
pressure (26). Two studies reported no relationship
between sleep and blood pressure in participants
under 60 years of age (25,26).
Sex-related findings. One study reported that short
sleep duration (5 h) was associated with hypertension only in women in a fully adjusted model (odds ratio, OR  1.72; 95% CI 1.07–2.75)
(30). This relationship remained significant after
a 5-year follow-up in unadjusted analyses, and
when adjusted for age and employment (6 h a
night OR  1.56; 95% CI 1.07–2.27; 5 h per night
OR  1.94; 95% CI 1.08–3.50). However, the associations were no longer significant after accounting for cardiovascular risk factors and psychiatric co-morbidity (OR  1.42; 95% CI 0.94–2.16;
OR  1.31; 95% CI 0.65–2.63, respectively). No
association between sleep duration and blood
pressure was detected in men in cross-sectional or
longitudinal analysis.
One study conducted a cross-cultural comparison between the Whitehall II study (UK) and the
Western New York Health (WNYH) study for correlates of sleep duration (27). They reported a relationship between hypertension and short sleep
duration (6 h) in women in the WNYH study in
models adjusting for only age and sex (OR  1.80;
95% CI 1.32–2.47, p  0.001). In the fully adjusted
models, there was an association in both studies
(OR  1.70; WNYH 95% CI 1.07–2.70, p  0.02;
Whitehall II 95% CI 1.13–2.56, p  0.01). There was
no association reported for men.
A Japanese study focusing on metabolic syndrome
examined the relationship between sleep duration
and hypertension in young male workers (between

52

E. Dean et al.

Table IV. Adjusted variables and main findings of the source studies.
First author, year

Study design

Sleep reference
(h/day)

Data analysis/adjusted
variables

Bjorvatn et al. (23)

Cross-sectional

7–7.99

Cappuccio et al.
(30)

Cross-sectional

7 8

Hierarchical linear
regression analysis: Step
1: unadjusted sleep
duration; Step 2: gender,
smoking, sleep duration
free time; Step 3: BMI;
Crude logistic regression
analyses using sleep
duration (workweek) as
the predictor for systolic
blood pressure (140
mmHg vs 140 mmHg)
and diastolic blood
pressure (90 mmHg vs
90 mmHg); Adjusted
logistic regression
analysis controlling for
gender, smoking, BMI
Reduced model: adjusted
for age and employment;
Fully adjusted: as above
plus alcohol consumption,
smoking, physical
activity, BMI,
cardiovascular disease
drugs, Short Form-36
mental and physical
health score, depression,
use of hypnotics

Longitudinal
(5-year
follow-up)

As above

Choi et al. (24)

Cross-sectional

7

Gangwisch et al.
(29)

Longitudinal
(8–10-year
follow-up)

7–8

Hall et al. (25)

Cross-sectional

7–8

Unadjusted

Model 1: Unadjusted; Model
2: daytime sleepiness,
depression, physical
activity, alcohol
consumption, salt
consumption, smoking,
pulse rate, gender; Model
3: model 2  education,
age, ethnicity; Model 4:
model 3  obesity, diabetes
Adjusted for age, sex, race,
educational attainment,
smoker, physical activity,
low-density lipoprotein
cholesterol and
symptoms of depression

Main findings
Unadjusted, both SBP and DBP were
higher with shorter sleep durations;
Controlled, these associations were no
longer significant; Sleep duration
5–5.99 h and 6–6.99 h became
significantly negatively related to SPB;
SBP: no relationship between sleep
duration and SBP 140 mmHg;
DBP: 5 h significantly related to
DBP 90 mmHg; SBP: 5–5.99 h and
6–6.99 h associated with decreased
risk of high SBP; DBP: no duration
significantly related

No consistent pattern of association in
men; Significantly higher prevalence of
htn in women sleeping 5 h in fully
adjusted model (OR  1.72 [95%
CI:1.07–2.75], p  0.037), with a
significant inverse linear trend across
decreasing hours of sleep (p  0.003);
Consistent, significant inverse
associations (p 0.05) between
duration of sleep and either SBP or
pulse pressure only among women, in
fully adjusted models
No consistent pattern of association in
men; Significantly higher incidence of
htn in women sleeping 5 h in
unadjusted and reduced model
analysis (6 h: OR  1.56 [95% CI
1.07–2.27], 5 h: OR  1.94 [95% CI
1.08–3.50]; Results not significant
after adjustment for cardiovascular
risk factors and psychiatric comorbidities
U-shaped relationship between sleep and
htn for subjects under age of 60,
lowest incidence at 7 h; BP
significantly differed (p  0.009) with
sleep duration 5 h for subjects under
60; No difference for subjects over 60
(p  0.623)
Unadjusted: significantly increased risk
of diagnosis in all sleeping 5 h with
younger age group (32–59)
(HR  2.10 [95% CI 1.58–2.79]); htn
in older adults 60–86 associated with
sleeping 9 h HR  1.54 [1.03–2.30];
Fully adjusted: relationship attenuated
but still significant for 5 h, especially
young (32–59) HR  1.60 [1.19–2.14]
No relationship between sleep and mean
BP in unadjusted or adjusted analysis

(Continued)

Sleep duration and blood pressure

53

Table IV. (Continued).
Study design

Sleep reference
(h/day)

Data analysis/adjusted
variables

Kawada et al.
(26)

Cross-sectional

6 vs 6

Knutson et al.
(31)

Cross-sectional

Continuous
variable

Adjusted for drinking,
physical activity, sleep
duration, eating
breakfast, snacking
frequency, BMI
Partial adjustment: age, sex,
race; Full: partial  snoring,
day time sleepiness,
income, education,
smoking status, BMI,
physical activity, alcohol
use, AND 5-year change
in smoking, alcohol, BMI,
and physical activity
As above

First author, year

Longitudinal (5
years)

Lima-Costa et al.
(22)

Cross-sectional

7 8

Lopez-Garcia
et al. (32)

Cross-sectional

7

Longitudinal
(2-year
follow-up)
Stranges et al.
(27)

Comparative
crosssectional

van den Berg
et al. (28)

Cross-sectional

6–8

7-  8 for
self-report;
6-  7 for
actigraphy
group

Model 1: unadjusted;
Model 2: age, gender;
Model 3: 2  skin color,
diabetes mellitus,
depressive symptoms,
body mass index, and
hypnotic or sedative meds
Adjusted for age, sex, physical
activity, BMI, smoking,
alcohol consumption,
coffee, consumption,
education level, number of
social ties, perceived health,
depression, number of
chronic disease, arousal
from sleep at night,
anxiolytic intake
As above

Analyzed correlates of sleep
duration including marital
status, socioeconomic
status, BMI, current
smoker, current alcohol,
low vs. high physical
activity, Short Form-36
score, depressive
symptoms, diabetes
mellitus); adjusted odds
ratio for age and sleep
Model 1: age, gender; Model
2: model 1BMI,
smoking, depression
symptoms, sleep medication
use, diabetes mellitus,
myocardial infarction,
stroke, daytime napping

Main findings
Sleeping 6 h not significantly
associated with high BP (OR  1.12
[0.90–1.31])

Partial adjustment: shorter sleep
durations significantly associated with
higher SBP (p  0.006) and DBP
(p  0.001); Full adjustment: no
significant association between sleep
duration and SBP (p  0.07) or DBP
(p  0.09)

Partial adjustment: short sleep associated
with smaller decreases or increases in
SBP (p  0.02), DBP (p  0.001), and
increased odds of incident htn
(OR  1.37 [95% CI 1.05–1.78]): 1-h
sleep reduction  37% increase in odds;
Full adjustment: sleep duration not
associated with change in SBP (p  0.09);
significantly associated with change in
DBP (p  0.03); increased odds of htn
attenuated (OR  1.3 [0.96–1.75])
Usual sleep duration not associated with
prevalent htn in unadjusted or
adjusted models

No association between sleep duration
and prevalent htn, before or after
adjustment, or using a htn cut-off of
160/100 mmHg or systolic htn only;
No association between sleep duration
and SBP, DBP, or pulse pressure

No association between sleep duration
and incident htn; Result unchanged
when analysis repeated for men and
women separately
Significant relationship between
hypertension and short sleep duration
(6h) in women in the WNYH study
in models adjusting for only age and
sex OR:1.80 [1.32–2.47] p  0.001;
In fully adjusted models, significant
association of short sleep duration and
htn in women, in both studies
OR  1.70 [WNY 1.07–2.70 p  0.02;
Whitehall 1.13–2.56 p  0.01]
No association between sleep and htn, even
using a lower cut-off value for htn; In
multivariable linear analysis, sleep duration
was not associated with SBP or DBP

htn, hypertension; SBP, systolic blood pressure; DBP, diastolic blood pressure; OR, odds ratio; HR, hazard ratio; CI, confidence interval.

54

E. Dean et al.

36 and 60 years of age) (26). This study used 6 h
of sleep as its reference group, and observed that
sleeping 6 h a day was not associated with hypertension (OR  1.12; 95% CI 0.90–1.31).
Several studies analyzed data from elderly men
and women and reported that sleep duration and
blood pressure were not associated in either sex
(28,32). In a young middle-aged population (between
33 and 45 years of age), one study reported that the
association between sleep and blood pressure was
comparable for men and women (31).
Discussion
Among the studies we reviewed, there was heterogeneity in sample sizes, methods of measuring blood
pressure and sleep duration, data collection, and the
control of confounding variables. Despite these discrepancies, two relationships emerged that highlighted age- and sex-specific effects.
With respect to the age-related association between
habitual short sleep duration and blood pressure, the
evidence supported an association between the likelihood of hypertension among individuals 60 years of
age who slept 5 h each night (24,29,31). In adjusted
models, short sleep duration and hypertension were
unrelated in people 60 years old (22,24,28,29,32).
Table I shows that four of the five studies (24,28,29,32)
reporting age-related findings (either before or after
attenuation of variables) scored either 16 (24,28) or 19
(29,32) on the Downs and Black Quality Index, which
were among the highest scores for quality assessment,
while one scored 12 (22). The quality of these studies
adds credibility to their results.
Mechanisms have been proposed for an agerelated association between habitual sleep duration and
blood pressure. First, lifestyle changes associated with
retirement in high-income countries from where the
source studies originated may allow for more opportunities for relaxation to compensate for short night-time
sleep durations (28). Second, individuals with disorders
such as hypertension, obesity and diabetes are less likely
to survive into their later years (29).
The second main relationship was sex-specific,
where women who slept 5–6 h each night were at
higher likelihood of hypertension (17,30). The precise mechanism explaining this sex-specific relationship is not known. One explanation may be the role
of hormonal and psychosocial changes associated
with menopause (30). Studies have shown that there
is no relationship between short sleep duration and
hypertension in women 60 years (28,32). In our
systematic review, the strongest relationship between
habitual short sleep duration (5 h or 6 h) and
hypertension seems to be among younger women
between 30 and 60 years of age.
Our findings are of interest because they are relevant to diverse populations with chronic conditions.
Given the variability among studies, our results may

be applicable to adults living in a range of countries.
Most studies collected data from populations in the
northern hemisphere; thus, other populations are
underrepresented. Also, the relationship between
short sleep duration and blood pressure is consistent
with research supporting that short sleep duration
has effects on lifestyle-related conditions such as
metabolic syndrome and obesity (23–26,30). Hence,
these findings could inform the practices of a number
of health care practitioners who could address sleep
as a modifiable risk factor in mitigating these prevalent and costly chronic conditions.
The relationship between habitual sleep duration,
hypertension and other systemic conditions is complex; isolating one condition from another when
interpreting data is difficult. Sleep-disordered breathing is associated with short sleep duration, and
hypertension is highly co-morbid with sleep apnea
(34,35). The metabolic syndrome and its components also have been associated with sleep duration
(23,24), and each component is likely interrelated;
the relationship between obesity and sleep duration
is generally well established (36). Obesity and hypertension, however, are often related co-morbid conditions (37). Furthermore, some conditions associated
with habitual short sleep duration may only be
detected after a period of latency. Given the complexity of these relationships, to determine directionality warrants detailed study.
Although the effect of sleep deprivation on neural cardiovascular control, especially muscle sympathetic nerve activity, is controversial (14), several
mechanisms can be proposed by which habitual
short sleep duration could elevate blood pressure.
First, short-term sleep deprivation has been reported
to increase the activity of the sympathetic nervous
system. The synthesis of catecholamines is augmented via activation of the suprachiasmatic nucleus
(15,38). This, in turn, leads to vessel constriction,
subsequent increases in blood pressure and adverse
vascular remodeling (39). Second, blood pressure
and heart rate naturally follow a diurnal pattern.
They are lower during sleep; thus, prolonged periods of wake time could predispose an individual to
unnatural increases in blood pressure and heart rate
with less reprieve time (40). More waking time may
also lead to greater opportunity to engage in
unhealthy behaviors that influence blood pressure
(e.g. caffeine consumption, poor dietary habits,
exposure to emotional stress), and that stimulate
arousal and negatively impact the cardiovascular
and cerebrovascular systems (40,41).
The quality of our results directly reflects the
quality of the source studies. Use of the Downs and
Black Quality Index for quality assessment provided
a profile of each study alerting the reviewers to its
methodological strengths and weaknesses (20). In
interpreting the data, higher credence was given to
higher scoring articles. While this index is useful in

Sleep duration and blood pressure
examining both observational and experimental
studies, the scores of the studies in our review were
low; the index has questions pertaining to experimental methods, however we reviewed strictly observational studies. In the assessment of longitudinal,
non-randomized studies, the maximum achievable
score is 19 (20). Common among the studies was the
lack of randomization, and blinding of researchers
and participants. Ultimately, these methodological
limitations negatively impacted scores on the Downs
and Black Quality Index.
All the source studies were cross-sectional and/or
longitudinal in design. Cross-sectional studies allow
for comparison of variables at the same time points,
while longitudinal studies allow for the reporting of
more observations over time. Given their observational nature, however, they are more susceptible to
bias than experimental studies and cannot establish
causality.
The methodology across source studies was
inconsistent. Commonly, blood pressure was measured by trained professionals using standard sphygmomanometers. The timing and averaging of
measurements, however, varied across studies. Studies also differed with respect to their definitions of
high blood pressure or hypertension (Table III); this
limitation could have affected the recorded prevalence or incidence of high blood pressure or hypertension. Another limitation across studies was the use
of self-report as a measure of habitual sleep duration.
However, good agreement has been reported in the
literature between self-reported sleep duration, and
actigraphic monitoring or the gold standard polysomnography (40,43). There were also discrepancies
among studies as to the confounding variables for
which investigators chose to control.
Blood pressure measurement was consistent in
one respect and that was related to blood pressure
being taken by someone other than the subject.
However, that home and ambulatory blood pressures are more valid is a consideration for future
studies (44).
One final limitation is reflected in the interpretation of the data. In eight of the 11 articles reviewed,
approximately 21% of study sample sizes comprised
the extremes (6 h and 8 h) of reported habitual
sleep duration (22,23,25,28–32). Thus, the applicability of our main findings of this systematic review
needs to be interpreted cautiously.
Growing evidence supports that short habitual
sleep duration is associated with metabolic disorders
such as obesity, diabetes and hypertension (33). If
sleep duration is a modifiable risk factor for hypertension and subsequently cardiovascular disease,
then formal assessment of sleep quality and quantity
warrants being assessed and potentially managed as
conscientiously as an individual’s functional capacity.
Given there are compelling explanations associating
reduced habitual sleep duration and blood pressure,

55

interventions involving sleep hygiene whilst visiting
a health care professional could serve to blunt this
rising trend of high blood pressure and its sequelae,
not to mention the importance of restorative sleep
on health and function.
Representative prospective studies with adequate
sample size and long-term duration are indicated.
These should include repeated objective measures of
blood pressure and habitual sleep duration, and control for confounders to help build evidence of causality. Although conducting randomized controlled
trials that impose short sleep duration on healthy
individuals is unethical, observation of the effect of
longer sleep durations in sleep-deprived individuals
with hypertension could be useful to help elucidate
this relationship.
The following variables are known to affect blood
pressure: age, sex, race, physical activity, obesity,
diet, caffeine intake, alcohol intake, salt and potassium intake, type II diabetes mellitus, smoking,
socioeconomic status, mental status (as measured
by Short Form-36), family history of hypertension
(45). Future research needs to standardize and control these variables. Various exclusion criteria should
also be considered when designing future studies
related to sleep. The following are recommended for
exclusion from future studies as they may interfere
with identifying a directional relationship: sleep disorders (e.g. dyssomnias and parasomnias), sleep
disorders related to mental and/or neurological conditions (e.g. psychoses and dementia), sleep disordered breathing (e.g. apneas), psychological
disorders, cancer, and cardiovascular, respiratory or
metabolic diseases (45).
We recommend that future studies examining
the relationship between habitual sleep duration
and hypertension incorporate consistent methodology. Blood pressure measures, for example, should
be taken at a consistent time each day using a standardized technique. Sleep duration, if not measured objectively, should be assessed in a
standardized manner such as with a self-report
sleep diary.
To conclude, habitual sleep duration and blood
pressure are associated specifically in women
and adults under 60 years of age. Controlled studies are needed to elucidate the factors that apparently confound this relationship, and the degree to
which profiles of patients’ habitual sleep could
augment the diagnosis of hypertension and inform
sleep recommendations to prevent or manage
hypertension.
Acknowledgments
The investigators acknowledge the support and
assistance of Charlotte Beck, Dr Michael Bodner,
Dr Lara Boyd, Dr Stanley Coren, Dean Giustini,
Dr Teresa Liu-Ambrose and Dr Darlene Reid.

56

E. Dean et al.

Declaration of interest: The authors report no
conflicts of interest. The authors alone are responsible for the content and writing of the paper.
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