Table 3

Characteristics of the studies included in the meta-analysis (in order of baseline year)

First author, publication yearAscertainment of sleep (ref vs exposure)Ascertainment of mortalityAdjustment for confounders
Kaplan, 198742Questionnaire
Nighttime sleep
7.0–8.0 vs <7.0 h
7.0–8.0 vs >8.0 h
Death certificate
All cause
Age, self-reported health status
Kronholm, 201129Questionnaire
Nighttime sleep
7.0–8.0 vs ≤5.0 h
7.0–8.0 vs ≥10.0 h
Death certificate and hospital discharge register
All cause and CVD
None
Gale, 199843Questionnaire
Nighttime sleep
9.0 vs ≤7.0 h
9.0 vs ≥12 h
Death certificate
All cause
Age, sex, geriatrician’s diagnoses of illness, social class, systolic BP, BMI
Branch, 198444Questionnaire
Nighttime sleep
7.0–8.0 vs 1.0–6.0 h
7.0–8.0 vs >8 h
Death certificate
All cause
None
Gangwisch, 200845Questionnaire
Nighttime sleep
7.0 vs ≤5.0 h
7.0 vs ≥9.0 h
Death certificate and proxy interviews
All cause
Age, physical activity, smoking, depression, sex, education, living alone, low income, daytime sleepiness, nighttime awakening, ethnicity, sleeping pill use, BMI, diabetes, hypertension, general health, cancer
Mallon, 200230Questionnaire
Nighttime sleep
6.0–8.0 vs <6.0 h
6.0–8.0 vs >8.0 h
Death certificate
All cause
Age, living alone, not being married, smoking, diabetes, CVD, depression, insomnia, BMI, joint pain, respiratory disease, gastrointestinal disease, habitual sleeping pills use, habitual snoring
Jung, 201339Questionnaire
Nighttime sleep
7.0–7.9 vs 6.0 h
7.0–7.9 h vs ≥9.0 h
Daytime sleep
None vs ≥0.5 h
Death certificate (90%), or notice from a family member or published obituary (10%)
All cause
Age, nap duration, depression, exercise, education, smoking, alcohol consumption, hypertension, diabetes, coronary heart disease, stroke, cancer, sleep-related medications and postmenopausal oestrogen
Burazeri, 200336Questionnaire
Daytime sleep
None vs ≥2.0 h
Death certificate
All cause and CVD
Age
Rumble, 199246Questionnaire
Nighttime sleep
4.0–9.9 vs <4.0 h
4.0–9.9 vs ≥10.0 h
Death certificate and patient records
All cause
Sex, health ‘risk’, sleep medication
Ruigomez, 199547Questionnaire
24 h sleep
7.0–9.0 vs ≤5.0 h
7.0–9.0 vs >9.0 h
Death certificate
All cause
Age, sex, education, perceived health status
Stone, 200934Questionnaire
Nighttime sleep
6.0–8.0 vs <6.0 h
6.0–8.0 vs >8.0 h
24 h sleep
8.0–8.9 vs <6.0 h
8.0–8.9 vs ≥10.0 h
Death certificate
All cause, CVD, cancer and other
Age, BMI, history of at least one medical condition (diabetes, Parkinson's disease, dementia, COPD, non-skin cancer and osteoarthritis), CVD, hypertension, walks for exercise, alcohol use, smoking status, depression, cognitive impairment, oestrogen use, benzodiazepine use
Cohen-Mansfield, 201248Questionnaire
Nighttime sleep
7.0–9.0 vs <7.0 h
7.0–9.0 vs >9.0 h
Death certificate
All cause
Age, sex, origin, marital status, education, income, had children, number of medications, comorbidity, subjective health, ADL and IADL limitations, cognitive difficulties, depressed affect
Kim, 201349Questionnaire
24 h sleep
7.0 vs ≤5.0 h
7.0 vs ≥9.0 h
Death certificate
All cause
Age, sex, ethnicity, education, marital status, hypertension, diabetes, alcohol consumption, energy intake, BMI, physical activity, hours spent daily watching television, smoking
Seki, 200150Questionnaire
24 h sleep
7.0 vs <6.0 h
7.0 vs ≥9.0 h
Death certificate
All cause
Age, sex, medical history (cerebrovascular disease, CVD, hypertension, diabetes, liver disease, renal disease, malignant neoplasm)
Lan, 200737Questionnaire
Nighttime sleep
7.0–7.9 vs <7.0 h
7.0–7.9 vs ≥10 h
Daytime sleep
None vs ≥2.0 h
Death certificate
All cause, CVD and cancer
Age, marital status, monthly income, cigarette smoking, alcohol consumption, BMI, exercise, disease history (heart disease, stroke and cancer), depression, afternoon nap duration
Leng, 201451Questionnaire
Daytime sleep
None vs ≥1.0 h
Death certificate
All cause
Age, sex, social class, educational level, marital status, employment status, BMI, physical activity level, smoking status, alcohol intake, depression, self-reported general health, hypnotic drug use, antidepressant use, COPD drug use, time spent in bed at night, self-reported pre-existing diseases, sleep apnoea
Yeo, 201352Questionnaire
24 h sleep
7.0 vs ≤5.0 h
7.0 vs ≥10.0 h
Death certificate
All cause, CVD, cancer, external cause, respiratory disease and other
Sex, educational attainment, BMI, cigarette smoking, alcohol consumption, hypertension, diabetes, CVD, metabolic syndrome
Kakizaki, 201331Questionnaire
24 h sleep
7.0 vs ≤6.0 h
7.0 vs ≥10.0 h
Death certificate
All cause, CVD, cancer and other
Age, sex, total caloric intake, BMI, marital status, education, job status, history of myocardial infarction, history of cancer, history of stroke, hypertension, diabetes, smoking, alcohol consumption, time spent walking, perceived mental stress, self-rated health
Werle, 201140Questionnaire
Nighttime
24 h sleep
≤8.0 vs >8.0 h
Death certificate, proxy interviews and patient records
All cause and CVD
Age, sex, education, number of family members living with the elderly, smoking, physical activity, BMI
Kripke, 201133Questionnaire and actigraphy
Nighttime sleep
7.0 vs ≤5.0 h
7.0 vs ≥9.0 h
Proxy interviews and social security death index
All cause
None
Castro-Costa, 201124Questionnaire
Nighttime sleep
7.0–7.9 vs <6.0 h
7.0–7.9 vs ≥9.0 h
Death certificate and proxy interviews
All cause
Age, schooling, marital status, working status, education, alcohol consumption, coffee consumption, smoking, physical exercises, depressive symptoms, cognitive functioning, psychoactive medications, physical functioning, arthritis ascertainment, systolic BP, HDL cholesterol ratio, diabetes, BMI
Chen, 201353Questionnaire
Nighttime sleep
7.0 vs ≤4.0 h 7.0 vs ≥9.0 h
Death certificate
All cause and CVD
Age, sex, living status, marital status, education, BMI, insomnia, excessive daytime sleepiness, pain, smoking, alcohol drinking, snorers, diabetes, hypertension, CVD, stroke, gouty arthritis, depression, hypnotics, total sleep time
Suzuki, 200941Questionnaire
24 h sleep
7.0 vs ≤5.0 h
7.0 vs ≥10.0 h
Death certificate
All cause and CVD
Age, sex, BMI, smoking status, alcohol consumption, frequency of physical activity, socioeconomic status, mental health, hypertension, diabetes
Ensrud, 201235Actigraphy
24 h sleep
>5.0 vs ≤5.0 h
Death certificate and proxy interviews
All cause
Age, race, site, health status, BMI, education, social support, alcohol intake, smoking, antidepressant, benzodiazepine, non-benzodiazepine sedative hypnotic use, medical conditions, cognition, baseline frailty status
Mesas, 201054Questionnaire
24 h sleep
7.0 vs ≤5.0 h
7.0 vs ≥11.0 h
Death certificate
All cause
Age, sex, BMI, educational level, municipality of residence, physical activity, smoking, alcohol consumption, coffee consumption, social links, perceived health, MMSE score, depression, Medical Outcomes Study 36-item Short Form Survey Physical and Mental Component Summary scores, instrumental activity of daily living limitations, hypertension, ischaemic heart disease, stroke, diabetes, cancer, COPD, Parkinson’s disease, arousal from sleep at night, use of anxiolytic medication
Lee, 201438Questionnaire
Nighttime sleep
<10.0 vs ≥10.0 h
Death certificate
All cause
Age, smoking, mood, overweight (BMI>23), medical conditions (diabetes, heart disease, history of cancer, COPD, history of stroke), frailty
Zuurbier, 201532Questionnaire and actigraphy
24 h sleep
6.0–7.5 vs<6.0 h
6.0–7.5 vs >7.5 h
Death certificate and patient records
All cause
Age, sex, ADL, smoking, diabetes, myocardial infarction, stroke, cognitive functioning, depressive symptoms, BMI, sleep medication, napping, apnoea
  • ADL, activities of daily living; BMI, body mass index; BP, blood pressure; COPD, chronic obstructive pulmonary disease; CVD, cardiovascular disease; HDL, high-density lipoprotein; IADL, instrumental activities of daily living; MMSE, Mini-Mental State Examination; Ref, reference.