Table 2.

Results of studies of sleep duration and all-cause mortality, arranged first by sleep measure and then alphabetically by cohort name. Results from the most fully-adjusted models from each study are presented.

						Significant Elevation in Mortality Risk Reporteda
Cohort Name (Country)	Age Range (Years)	Follow-Up (Years)	Cohort Size (N)	Percent Male	Findings for Specific Sleep Categoriesb	Short Sleep Effect Only	Long Sleep Effect Only	Short and Long Sleep Effect (U- Shaped)	No Sleep Effect
Survey Sleep Measure: Nighttime Sleep
American Cancer Society (USA) [5]	30-95+	6	823,065	44%	<4, 4, 5, 6, 7, 8, 9, ≥10			Malesc Femalesc
Cancer Prevention Study II (USA) [3]	30-102	6	1,116,936	43%	3f, 4mf, 5mf, 6mf8mf, 9mf, ≥10mf			Malesc Femalesc
Dalarna County postal survey (Sweden) [8]	45-65	12	1,870	48%	<6, 6-8, >8m		Males		Females
Elderly cohort (USA) [10]	65-98	3.5	1,855	34%	<5, 5, 6, 7, 8, ≥9				Males Females
FINRISK Surveys (Finland) [11]	25-64	35	23,290	49%	≤5mf, 6f, 7-8, 9f, ≥10mf			Males Females
Japan Collaborative Cohort Study for Evaluation of Cancer (Japan) [21]	40-79	Median=14.3	98,634	42%	≤4mf, 5, 6, 7, 8f, 9mf, ≥10mf			Males Females
Massachusetts Health Care Panel Study (USA) [24]	66-98	5	1,235	38%	1-6 or ≥9h vs. 7-8				Males Females
Miyagi Prefecture survey (Japan) [25]	≥40	4	4,318	40%	7-8 vs. ≤6 or ≥9				Combined sexes
National Health and Nutrition Examination Survey I (USA) [26]	32-86	8-10	9,789	37%	≤5, 6, 7, 8*, ≥9*		Combined sexes
Rancho Bernardo Study (USA) [98]	60-96	19	2,001	44%	<6, 6, 7, 8, ≥9f		Females		Males
Whitehall II Cohort (UK) [35]	35-55	Mean=17.1	10,308	67%	≤5, 6, 7, 8, ≥9				Combined sexes
Survey Sleep Measure: 24-Hour Sleep
Chinese Longitudinal Healthy Longevity Survey (CLHLS) (China) [97]	65-100+	3	12,671	43%	≤5m, 6, 7, 8, 9, ≥10m			Males	Females
Finnish Twin Cohort (Finland) [1]	24-101	21	21,268	48%	<7mf, 7-8, >8mf			Males Females
Health Interview Study of Barcelona (HISB) (Spain) [14]	≥65	5	1,219	38%	<7, 7-9, >9				Males Females
National Health Interview Survey (NHIS) (USA) [115]	≥18	16	38,891		≤6, 7-8, ≥9			Combined sexes
Nurses’ Health Study (USA) [29]	40-65	14	82,969	0%	≤5, 6, 7, 8f, ≥9f		Females
Ohsaki Cohort Study (Japan) [116]	40-79	Mean=10.8	49,256	48%	≤6, 7, 8*, 9*, ≥10*		Combined sexes
Scottish working cohort (Scotland) [30]	<60 females; <65 for males	25	6,797	86%	<7, 7-8, >8				Males Females
Shizuoka Study (Japan) [31]	65-85	6	11,395	51%	≤5, 6, 7, 8m, 9m, ≥10mf		Males Females
Spanish cohort (Spain) [32]	≥60	Mean=6.8	3,820	44%	≤6f, 7, 8m, 9m, ≥10mf		Males	Females
Study of Osteoporotic Fractures (USA) [33]	≥69	Mean=6.9	8,101	0%	<6, 6-7, 8, 9f, ≥10f		Females
Survey Sleep Measure: Bedtime and Waking Time
Bambui Health and Ageing Study (Brazil) [6]	≥60	23	1,512	39%	<6, 6, 7, 8, ≥9*			Combined sexes
Cross-Sectional and Longitudinal Aging Study (Israel) [99]	75-94	20	1,166	55%	<7, 7-9, >9*			Combined sexes
Department of Health and Social Security Survey (UK) [9]	≥65	10	862	51%d	<7, 8, 9, 10, 11, ≥12*			Combined sexes
Gifu Prefecture cohort study (Japan) [12]	20-67	Mean=11.9	5,322	46%	<7m, 7-8, 9, ≥10		Males		Females
Jichi Medical School Cohort Study (Japan) [22]	19-93	Mean=8.2	11,325	39%	<6m; 6; 7; 8; ≥9		Males		Females
Kiryat Yovel Community Health Study (Israel) [23]	≥50	9-11	1,842	46%	<6, 6-8, >8				Malese Femalese
Survey of Health and Living Status of the Elderly in Taiwan (Taiwan) [34]	≥64	10	3,079	57%	<7, 7, 8f, 9f, ≥10mf			Males Females
Survey Sleep Measure: Not Clearly Specified
Chin-Shan Community Cardiovascular Cohort Study (Taiwan) [7]	≥35	Median=15.9	3,430	56%	≤5; 6, 7, 8, ≥9mf			Combined sexes
Health and Lifestyle Survey (UK) [13]	≥18	7	6,096	44%	<6, 6-8, ≥9			Malesc	Females
Human Population Laboratory (Alameda County study) (USA) [18]	38-94	17	1,454	NR	<7 or >8 vs. 7-8				Combined sexesg
Nottingham Longitudinal Study of Activity and Ageing (UK) [28]	≥65	5	1,042	NR	<4, 4-9, ≥10				Combined sexes
Polysomnography [36] and Wrist Actigraphy [4]
NIH-funded protocols (USA) [27]	58.7-91.4	Mean=12.8	184	46%	<6, ≥6				Combined sexes
Penn State Cohort Study (USA) [36]	≥20	14 (men); 10 (women)	1,741	42%	<6, ≥6				Males Females
Women’s Health Initiative Observational Study (USA) [4]	50-81	Mean=10.5	444	0%	<5f, 5-6.5, >6.5f			Females

^aResults were considered statistically significant on the basis of either stated P-values (P < 0.05) or 95% confidence intervals. “Combined sexes” denotes studies adjusting for sex. “Males” and “Females” indicate sex-specific results.

^bNumber in bold indicates the reference category;

^{*, m, and f}indicate a statistically significant elevation in mortality risk associated with a particular sleep category among: males and females in a model adjusted for sex; males in sex-specific analyses; and females in sex-specific analyses, respectively.

^cSignificance tests not reported for specific sleep categories; overall sleep effect inferred from text.

^dC Gale, University of Southampton, personal communication, 2012.

^eBurazeri et al. used the short sleeping category as the reference category and reported a significant difference for males between the longest sleepers (>8 hrs) and the shortest sleepers (<6 hrs). However, the confidence intervals for the effect estimates for the long and short sleepers relative to the average sleepers (6-8 hrs) all overlapped substantially, strongly suggesting that if the middle group had been the reference, no significant effect of either long or short sleep would have been found.

^gKaplan et al. did observe a significant elevation in mortality risk for 50-59 year olds, but no significant increases in risk for those 38-49, 60-69, or 70+ years of age.

NR denotes not reported.