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

Figures & data

Figure 1. Study selection flow chart.

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

		Study quality	External validity	Internal validity	Total score
Study	Year	(/ll)	(/3)	(/13)	(/32)
Bjorvatn et al. (23)	2006	8	0	5	13
Cappuccio et al. (30)	2007	9	0	8	17
Choi et al. (24)	2008	9	2	5	16
Gangwisch et al. (29)	2006	9	2	8	19
Hall et al. (25)	2008	9	2	5	16
Kawada et al. (26)	2008	7	0	4	11
Knutson et al. (31)	2009	9	2	8	19
Lima-Costa et al. (22)	2008	7	2	3	12
Lopez-Garcia et al. (32)	2009	9	2	8	19
Stranges et al. (27)	2008	8	1	7	16
Van den Berg et al. (28)	2007	9	2	5	16

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

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

First author	Year	Country	Study design	Study size	Subject age	Population source
Bjorvatn et al. (23)	2007	Norway	Cross-sectional	8860	40–5	Hordaland Health Study data (population-based, all born in Hordaland county 1953–1957)
Cappuccio et al. (30)	2007	UK	Cross-sectional Longitudinal (mean 5-year follow-up)	5766; Men: 4199; Women: 1567 3691; Men: 2686; Women: 1005	35–55	Whitehall II Study, white British civil servants; Excluded: ethnic groups other than white (n = 612) Normotensive population from cross-sectional study
Choi et al. (24)	2008	Korea	Cross-sectional	4222	>20	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
Gangwisch et al. (29)	2006	USA	Longitudinal (8-10-year follow-up)	4810	25-74	National Health and Nutrition Examination Survey (civilian, non-institutionalized US citizens); Excluded: those with diagnosed hypertension or blood pressure > 140/90 mmHg at baseline
Hall et al. (25)	2008	USA	Cross-sectional	1214	30-54	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
Kawada et al. (26)	2008	Japan	Cross-sectional	4941	36-60	Male employees of an electronics company; Excluded: past medical history of hypertension, dyslipidemia, and/or diabetes mellitus
Knutson etal. (31)	2009	USA	Cross-sectional Longitudinal (5-year follow-up)	578 505 (535 for incident hyper-tension analysis)	33–45	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
Lima-Costa et al. (22)	2008	Brazil	Cross-sectional	1423	60-95	Bambui Health Aging Study (community-based cohort in Bambui city; 81.7% of population >60 years old)
Lopez-Garcia et al. (32)	2009	Spain	Cross-sectional Longitudinal (2-year follow-up)	3686 890	>60	Population-based cohort representative of non-institutionalized Spanish population >60 years old Normotensive population from cross-sectional study
Stranges et al. (27)	2008	UK; USA	Comparative cross-sectional	UK: 6472; USA: 3027	UK: 45–69; USA: 35–79	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
van den Berg et al. (28)	2007	Netherlands	Cross-sectional	5058	58–98	Rotterdam Study (population-based cohort study, all >55 in district of Rotterdam invited to participate)

Table III. Measurement of sleep and blood pressure variables.

Study	BP measurement technique	Calculation of BP	Definition of htn or high BP	Method of sleep data collection	Specific question posed and/or technique used to analyze sleep data
Bjorvatn et al. (23)	1. Relaxed sitting position following 2 min rest; 2. Three automated BP measurements; 3. No talking during measurements	Averaged final 2 of 3 readings	Defined high BP as SBP >140 mmHg orDPB >90 mmHg	Self-report via self-administered questionnaire	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
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	Averaged final 2 of 3 readings	Defined htn as SBP/ DBPa 140/90 mmHg, or regular use of antihypertensive medication	Self-report questionnaire	"How many hours of sleep do you have on an average week night?"
Choi et al. (24)	1. In seated position following 10 min rest; 2. Two SBP and 2 DBP measurements with a 5 min interval between readings	Average of 2 readings	Defined htn as SBP or DBP > 130/85 mmHg	Self-report questionnaire	N/A
Gangwisch et al. (29)	1. Three BP measurements taken at the same sitting; 2. No reading taken if maximum cuff inflation >160 mmHg	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	Self-report questionnaire	“How many hours of sleep do you usually get a night (or when you usually sleep)?”
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	Defined high BP as SBP > 130 mmHg, or DBP > 85 mmHg, or use of antihypertensive medication	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 (Sunday-Thursday) and weekend nights (Friday, Saturday); Weekly average reported sleep duration calculated as the weighted average of weeknight and weekend values
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 readings 130/85 mmHg; lowest reading retained	Defined high BP as SBP > 130 mmHg and/or a 85 mmHg	Self-report	N/A
Knutson etal. (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	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	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
Lima-Costa et al. (22)	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	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
Lopez-Garcia 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	1. Self-report through home based personal interview at baseline; 2. Phone interview at follow-up	“How many hours do you usually sleep per day (including sleep at night and during the day)?”
Stranges et al. (27)	1. Sitting position using mercury sphygmomanometer; 2. 1st and 5 th 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	Self-report questionnaire	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)?”
van den Berg et al. (28)	1. Two blood pressure measurements in sitting at right brachial artery with random-0 sphygmomanometer	Average of 2 readings	Defined htn as SBP> 160 mmHg, or DBP> 100 mmHg, or current use of antihypertensive medication	Self-report by way of in-person home interview, and wrist actigraphy	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.

Table IV. Adjusted variables and main findings of the source studies.

First author, year	Study design	Sleep reference (h/day)	Data analysis/adjusted variables	Main findings
Bjorvatn et al. (23)	Cross-sectional	7-7.99	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 si40 mmHg) and diastolic blood pressure (>90 mmHg vs £90 mmHg); Adjusted logistic regression analysis controlling for gender, smoking, BMI	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
Cappuccio et al. (30)	Cross-sectional Longitudinal (5-year follow-up)	7–<8	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 As above	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 co-morbidities
Choi et al. (24)	Cross-sectional	7	Unadjusted	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 0 = 0.623)
Gangwisch et al. (29)	Longitudinal (8-10-year follow-up)	7–8	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	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]
Hall et al. (25)	Cross-sectional	7–8	Adjusted for age, sex, race, educational attainment, smoker, physical activity, low-density lipoprotein cholesterol and symptoms of depression	No relationship between sleep and mean BP in unadjusted or adjusted analysis
Kawada et al. (26)	Cross-sectional	<6 vs >6	Adjusted for drinking, physical activity, sleep duration, eating breakfast, snacking frequency, BMI	Sleeping >6h not significantly associated with high BP (OR= 1.12 [0.90–1.31])
Knutson et al. (31)	Cross-sectional Longitudinal (5 years)	Continuous variable	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	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 O = 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])
Lima-Costa et al. (22)	Cross-sectional	7-<8	Model 1: unadjusted; Model 2: age, gender; Model 3:2 + skin color, diabetes mellitus, depressive symptoms, body mass index, and hypnotic or sedative meds	Usual sleep duration not associated with prevalent htn in unadjusted or adjusted models
Lopez-Garcia et al. (32)	Cross-sectional Longitudinal (2-year follow-up)	7	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	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
Stranges et al. (27)	Comparative cross-sectional	6-8	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	Significant relationship between hypertension and short sleep duration (<6h) in women in theWNYH 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 £ = 0.02; Whitehall 1.13-2.56 £ = 0.01]
van den Berg et al. (28)	Cross-sectional	7–< 8 for self-report; 6-<7 for actigraphy group	Model 1: age, gender; Model 2: model 1+BMI, smoking, depression symptoms, sleep medication use, diabetes mellitus, myocardial infarction, stroke, daytime napping	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.

Bjorvatn B, Sagen IM, Oyane N, Waage S, Fetveit A, Pallesen S, . The association between sleep duration, body mass index and metabolic measures in the Hordaland Health Study. J Sleep Res. 2007;16:66–76.

 PubMed Web of Science ®Google Scholar

Cappuccio FP, Stranges S, Kandala NB, Miller MA, Taggart FM, Kumari M, . Gender-specific associations of short sleep duration with prevalent and incident hypertension: The Whitehall II Study. Hypertension. 2007;50: 693–700.

 PubMed Web of Science ®Google Scholar

Choi KM, Lee JS, Park HS, Baik SH, Choi DS, Kim SM. Relationship between sleep duration and the metabolic syndrome: Korean National Health and Nutrition Survey 2001. Int J Obesity. 2008;32:1091–1097.

 PubMed Web of Science ®Google Scholar

Gangwisch JE, Heymsfield SB, Boden-Albala B, Buijs RM, Kreier F, Pickering TG, . Short sleep duration as a risk factor for hypertension: Analyses of the first national health and nutrition examination survey. Hypertension. 2006;47: 833–839.

 PubMed Web of Science ®Google Scholar

Hall MH, Muldoon MF, Jennings JR, Buysse DJ, Flory JD, Manuck SB. Self-reported sleep duration is associated with the metabolic syndrome in midlife adults. Sleep. 2008;31: 635–643.

 PubMed Web of Science ®Google Scholar

Kawada T, Okada K, Amezawa M. Components of the metabolic syndrome and lifestyle factors in Japanese male workers. Metab Syndr Relat D. 2008;6:263–266.

 Google Scholar

Knutson KL, Van Cauter E, Rathouz PJ, Yan LL, Hulley SB, Liu K, . Association between sleep and blood pressure in midlife: The CARDIA Sleep Study. Arch Intern Med. 2009; 169:1055–1061.

 PubMedGoogle Scholar

Lima-Costa MF, Peixoto SV, Rocha FL. Usual sleep duration is not associated with hypertension in Brazilian elderly: The Bambui Health Aging Study (BHAS). Sleep Med. 2008;9: 806–807.

 Google Scholar

Lopez-Garcia E, Faubel R, Guallar-Castillon P, Leon-Munoz L, Banegas JR, Rodriguez-Artalejo F. Self-reported sleep duration and hypertension in older Spanish adults. J Am Geriatr Soc. 2009;57:663–668.

 PubMed Web of Science ®Google Scholar

Stranges S, Dorn JM, Shipley MJ, Kandala NB, Trevisan M, Miller MA, . Correlates of short and long sleep duration: A cross-cultural comparison between the United Kingdom and the United States: The Whitehall II study and the Western New York Health Study. Am J Epidemiol. 2008;168:1353–1364.

 PubMed Web of Science ®Google Scholar

van den Berg JF, Tulen JHM, Neven AK, Hofman A, Miedema HME, Witteman JCM, . Sleep duration and hypertension are not associated in the elderly. Hypertension. 2007;50:585–589.

 PubMed Web of Science ®Google Scholar