Clinical reviewHas adult sleep duration declined over the last 50+ years?
Introduction
It has been widely stated that modern industrialized societies have become sleep-deprived. Some studies have suggested that average sleep duration has declined over the last few decades [1], [2], [3], [4]. Such findings, combined with extensive epidemiologic evidence associating short sleep with health risks *[5], [6], *[7] and experimental evidence of adverse effects of sleep deprivation [8], [9], [10], have provoked widespread concern that chronic insufficient sleep has become a public health crisis.
However, recent reviews of self-reported data have cast doubt on whether nighttime sleep or 24-h sleep has decreased in recent decades, and whether there has been an increased prevalence of short sleep (<6 h), for which risks have been most clearly established. For example, a review of eight studies by Knutson et al. found no significant 31-y trend (1975–2006) towards a higher prevalence of self-reported nighttime sleep of ≤6 h [11]. Bin et al. reviewed 12 studies from 15 countries assessed from the 1960s–2000s, and found that sleep duration had increased in seven countries, decreased in six countries, and had not clearly changed in two countries [12]. In a subsequent meta-analysis of 38 studies conducted in 10 countries in the 1970s–2000s, Bin et al. [13] found that average 24-h sleep duration had increased in most countries (including the US), and that the prevalence of sleeping ≤ 6 h had decreased in most countries (including the US). Rowshan Ravan et al. studied 36-y trends (1968–2004) in sleep duration among Swedish women, and found no change in 50-y old women, and a decline of only 15 min in 38-y old women [14]. Moreover, Bonke reviewed five representative time-use studies spanning 1964–2009, and concluded that “the same number of hours is slept today as in the mid-1960s, with nearly the same prevalence of short and long sleepers” [15].
Discrepancies between studies of population temporal trends in sleep duration can be attributed to multiple factors, including characteristics and representativeness of the respondents, wording of the questions, and instructions given to respondents [16], [17]. Perhaps the biggest limitation of this literature is that it has been limited to self-reports of sleep duration (some of which were retrospective), which can be inaccurate [18], [19] due in part to response biases. The aim of this review was to examine whether there has been a decline over the past five decades in sleep duration, as indexed by objective data.
Section snippets
Methods
The search of the literature was modeled after a previous meta-analysis by Ohayon et al., which assessed objective sleep patterns across age [20]. PubMed, PsychLit, selected journals, and reference lists of located manuscripts were searched for studies published between 1960 and 2013 which met the following criteria: 1) inclusion of presumably healthy adults (as described by the authors), participant ages ≥18 y without sleep problems; 2) report of all-night average total sleep time (TST)
Results
The intercepts and slopes of the regression lines of age vs. TST did not differ for studies conducted between 1960–1989 and 1990–2013 (Fig. 1). In the regression analysis across all data points (n = 257), there was no significant association of year of study with TST (b = 0.03, p = 0.56) (Fig. 2), nor was there a significant association of study year with TST for any of the 10-y age categories (Fig. 3) (p = 0.40–0.92). Likewise, there was no significant association of year of study in analyses
Discussion
The results indicate relative stability of objectively-recorded sleep durations in healthy sleepers assessed over the last half-century. Similar results were found across all age groups, in both men and women, for both PSG and actigraphic data, and under conditions of fixed sleep periods and participants' usual sleep schedules. These data are consistent with recent comprehensive reviews that found no consistent or compelling evidence of significant decrements in self-reported sleep duration
Conflict of interest
The authors do not have any conflicts of interest to disclose.
Acknowledgments
This manuscript is dedicated to Dr. Richard R. Bootzin, our dear friend and colleague who passed away on December 4, 2014. Dr. Bootzin contributed to earlier drafts of this manuscript. Research supported by RO1-HL095799; R01-MD007716; R01-AG034588; R01-AG026364; R01-CA160245; R01-DA032922 the Cousins Center for Psychoneuroimmunology. Susan Noh assisted with this study.
References∗ (221)
- et al.
Effects of three weeks of mild sleep restriction implemented in the home environment on multiple metabolic and endocrine markers in healthy young men
Metabolism
(2013) Trends in short and long sleep in Denmark from 1964 to 2009, and the associations with employment, SES (socioeconomic status) and BMI
Sleep Med
(2015)Subjective reports of children's sleep duration: does the question matter? A literature review
Sleep Med
(2013)- et al.
Accuracy of sleep perceptions among insomnia sufferers and normal sleepers
Sleep Med
(2003) - et al.
Sleep in America: role of racial/ethnic differences
Sleep Med Rev
(2013) - et al.
Social jetlag and obesity
Curr Biol
(2012) - et al.
Sleep duration and mortality: rationale for sleep restriction
Sleep Med Rev
(2004) - et al.
Mortality related to actigraphic long and short sleep
Sleep Med
(2011) - et al.
Do we really want more sleep? A population-based study evaluating the strength of desire for more sleep
Sleep Med
(2008) - et al.
In search of lost sleep: secular trends in the sleep time of school-aged children and adolescents
Sleep Med Rev
(2012)
Sleep budgets in a globalizing world: biocultural interactions influence sleep sufficiency among Egyptian families
Soc Sci Med
EEG sleep patterns as a function of normal and pathological aging in man
J Psychiatr Res
Sleep characteristics of the human aged female
Compr Psychiatry
Effects of prolonged bed rest on EEG sleep patterns in young, healthy volunteers
Electroencephalogr Clin Neurophysiol
The number and duration of the episodes of the various EEG stages of sleep in young and older people
Electroencephalogr Clin Neurophysiol
The effect of sleep fragmentation on sleep and performance in younger and older subjects
Neurobiol Aging
Sleep is undisturbed in elderly, depressed individuals who have not sought health care
Biol Psychiatry
From early to late adulthood changes in EEG sleep of depressed patients and healthy volunteers
Biol Psychiatry
Quick-Stats: percentage of adults who reported an average of≤ 6 hours of sleep per 24-hour period, by sex and age group—United States, 1985 and 2004
MMWR Morb Mortal Wkly Rep
Trends in self-reported sleep duration and insomnia-related symptoms in Finland from 1972 to 2005: a comparative review and re-analysis of Finnish population samples
J Sleep Res
Associations between inadequate sleep and obesity in the US population: analysis of national health interview survey
BMC Public Health
Trends in self-reported sleep duration among US adults from 1985 to 2012
SLEEP
Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies
Sleep
Association between sleep duration and mortality is mediated by markers of inflammation and health in older adults: the health, aging and body composition study
Sleep
Sleep duration and mortality: a prospective study of 113 138 middle-aged and elderly Chinese men and women
Sleep
Cardiovascular effects of partial sleep deprivation in healthy volunteers
J Appl Physiol
Effects of sleep restriction and exercise deprivation on somatic symptoms and mood in healthy adults
Clin Exp Rheumatol
Trends in the prevalence of short sleepers in the USA: 1975-2006
Sleep
Sleeping at the limits: the changing prevalence of short and long sleep durations in 10 countries
Am J Epidemiol
Thirty-six-year secular trends in sleep duration and sleep satisfaction, and associations with mental stress and socioeconomic factors–results of the population study of women in Gothenburg, Sweden
J Sleep Res
Survey questions about sleep duration: does asking separately about weekdays and weekends matter?
Behav Sleep Med
Discrepancy between subjective symptomatology and objective neuropsychological performance in insomnia
Sleep
Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals: developing normative sleep values across the human lifespan
Sleep
Sleep and the epidemic of obesity in children and adults
Eur J Endocrinol
Objective and subjective components of the first-night effect in young nightmare sufferers and healthy participants
Behav Sleep Med
Trends and determinants of time in bed in Geneva
Switz J Clin Sleep Med
Mexicans must say adios to the 3-hour siesta
Wash Post
Where have all our naps gone? Or Nathaniel Kleitman, the consolidation of sleep, and the historiography of emergence
Anthropol Conscious
The Slumbering Masses. Sleep, Medicine, and Modern American Life
The medicalization of sleeplessness: a public health concern
Am J Public Health
Cross-national epidemiology of DSM-IV major depressive episode
BMC Med
Perceiving the community norms of alcohol use among students: some research implications for campus alcohol education programming
Int J Addict
Never enough sleep: a brief history of sleep recommendations for children
Pediatrics
Hypnotic drug use among 0-17 year olds during 2004-2011: a nationwide prescription database study
Scand J Public Health
Declining rates of physical activity in the United States: what are the contributors?
Annu Rev Public Health
The prevalence and health impact of shiftwork
Am J Public Health
Cited by (72)
Trends in sleep duration in the U.S. from 2004 to 2018: A decomposition analysis
2024, SSM - Population HealthTrends in sleep duration in Korea: The Korean time use survey
2023, Sleep MedicineAssociations of accelerometer-measured sedentary behavior and physical activity with sleep in older adults
2023, Journal of the Formosan Medical AssociationSleep function: an evolutionary perspective
2022, The Lancet NeurologyCitation Excerpt :This study showed that these populations do not sleep for 10–12 h as do non-human primates; rather, these people sleep for roughly 6–8 h. Another expectation about human sleep is that the artificial environments and electric lighting to which industrial populations (ie, people living in societies driven by technology) are exposed might greatly reduce sleep duration by delaying sleep onset. Although insomnia is much more prevalent in industrial populations than in humans living a hunter-gatherer lifestyle,2 the common assumption that sleep duration in industrial societies has declined over the past 50 years or more has been contradicted by the findings of a literature review of studies of sleep duration in healthy adults.3 Sleep duration in humans varies by age, with the longest periods in newborn babies (12–15 h), an intermediate duration in teenagers (9–10 h), and a lower amount of sleep in adulthood (6–8 h).
Sleep and Obesity
2022, Sleep Medicine Clinics
- ∗
The most important references are denoted by an asterisk.