Original ArticlesSleep duration, illumination, and activity patterns in a population sample: effects of gender and ethnicity
Introduction
Current knowledge of the population’s habitual sleep durations and circadian rhythms emanates primarily from questionnaire surveys and laboratory polysomnographic studies Kripke et al 1979, Gallup 1979, Gallup 1995, Schoenborn 1986, Webb and Campbell 1979. Unfortunately, laboratory investigations have shown that subjective questionnaire reports of individuals’ sleep are often inaccurate (Carskadon et al 1976). Moreover, laboratory samples are distorted both by the peculiar laboratory environment and by recruitment methods, which do not yield representative samples of the population.
The past two decades have furnished a converging series of studies that point to a gradual decline in the population’s sleep duration. Williams’ landmark study (Williams et al 1974) found that volunteers slept approximately 7 hours in laboratory polysomnographic recordings. This observation suggested that the average adult might be sleeping less objectively than the proverbial 8 hours, which was popularly believed to be the mode. Indeed, survey data had indicated that ≥ 8 hours was the modal sleep time reported four decades ago (Kripke et al 1979). A Gallup survey (Gallup 1979) also found that 8 hours of sleep was the reported mode. Several years later, the National Health Interview Survey showed that 67% of individuals ranging from 45–64 years of age reportedly slept 7–8 hours at night (Schoenborn 1986).
There was some consternation when the Gallup survey of habitual sleep duration was repeated 15 years later, finding that the modal self-estimated sleep had dropped to 7 hours (Gallup 1995). Notably, in the 1995 survey, 49% of participants reported sleep problems, whereas 36% had reported problems in the landmark survey, “Sleep in America” (Gallup 1991). More recently, the Omnibus Sleep in America Poll (OSAP) observed average reported sleep of 6.57 hours (Gallup 1998).
Objective measures are essential to investigate current sleep durations in the population. Unfortunately, a number of methodological concerns limit the utilization of polysomnography in epidemiological studies Agnew et al 1966, Edinger et al 1997, Hauri and Olmstead 1989, Moses et al 1972, Reynolds et al 1992, Toussaint et al 1995, van Hilten et al 1993. In this investigation, wrist actigraphy (Actillume) was used to monitor sleep and wakefulness patterns, despite some inherent limitations. This methodology was chosen because it facilitates compliance and permits representative recruitment Sadeh et al 1995, Tryon 1991. Furthermore, the Actillume also provides data on activity and illumination patterns in the sample.
Although the influences of the light/dark cycle have been demonstrated in numerous experimental paradigms, little attention has been paid to actual environmental illumination in the population. Evidence from our laboratory has shown relatively little daylight illumination in young and older adults Campbell et al 1988, Cole et al 1995, Okudaira et al 1983, Savides et al 1987. This study expanded on these previous reports by examining illumination exposure in a population sample. Activity, an important circadian behavioral marker, was also considered Aschoff 1969, Moore-Ede et al 1983, Stephan and Nunez 1977. To date, inconsistent findings have been reported regarding the effects of gender and age on activity patterns Brown et al 1995, Jean-Louis et al 1997a, Jean-Louis et al 1997b, Lieberman et al 1987, Renfrew et al 1991, van Hilten et al 1993.
This analysis focuses on gender and ethnicity effects on sleep and wakefulness, illumination, and activity patterns in a sample of adults ranging from 40 to 64 years of age in the city of San Diego. Additionally, we adjusted for effects of age, time reference (i.e., Daylight Saving Time vs. Standard Time), and work status.
Section snippets
Participants and procedure
Wrist activity and illumination data were gathered from volunteers who were recruited by random telephone calls from July 1990 through June 1994 as part of a survey assessing the prevalence of sleep disorders in the city of San Diego. The present analyses were based on a portion of the sample selected for complete data. Telephone calls placed to numbers selected at random were utilized to obtain as representative a sample as possible of San Diego residents (age range: 40–64 years). Consenting
Results
Volunteers (women = 144, men = 129) were all community residents of the city of San Diego (see Table 1). Of the sample, 77% were non-Hispanic Whites and the remaining 23% comprised an aggregate of Hispanics, African Americans, Native Americans, Asians, and Others. Women holding office jobs represented 34% of the sample, and men with office jobs were 41% of the sample, totaling 75% (78.2% for White and 63.0% for minority volunteers).
The remaining 25% of the volunteers indicated that they were
Sleep profile
The present actigraphic investigation demonstrated that the adult population (ages 40–64) sleeps considerably less than was once thought, at least in San Diego. The average sleep recorded for men and women was 373 min, which is somewhat surprising, considering that the current nosologic characterization of insomnia emphasizes sleep durations of less than 6.5 hours (ASDA Diagnostic Classification Steering Committee, 1990). This actigraphic finding corroborates contemporary questionnaire surveys
Acknowledgements
This research was supported by NIA (AG12364 and AG02711) and NHLBI (HL55983 and HL40930). We thank Mary Anne Mowen, William J. Mason, Daniel J. Mullaney, Deborah L. Wingard, Katharine M. Rex, Jeffrey A. Elliott and Terry Allen for their assistance in this study.
References (60)
- et al.
Exposure to light in healthy elderly subjects and Alzheimer’s patients
Physiol Behav
(1988) - et al.
Low illumination experienced by San Diego adultsassociation with atypical depressive symptoms
Biol Psychiatry
(1994) Light treatment for nonseasonal depressionspeed, efficacy, and combined treatment
J Affect Dis
(1998)- et al.
The first night effectan EEG study of sleep
Psychophysiology
(1966) - et al.
Use of wrist activity for monitoring sleep/wake in demented nursing-home patients
Sleep
(1997) Desynchronization and resynchronization of human circadian rhythms
Aerosp Med
(1969)- ASDA Diagnostic Classification Steering Committee (1990): The International Classification of Sleep Disorders:...
- et al.
Actigraphya means of assessing circadian patterns in human activity
Sleep
(1995) - et al.
Gender differences in the circadian temperature rhythms of healthy elderly subjectsrelationships to sleep quality
Sleep
(1989) - et al.
Self-reports versus sleep laboratory findings in 122 drug-free subjects
Am J Psychiatry
(1976)
Automnaic sleep/wake identification from wrist activity
Sleep
Ambulatory monitoring of light exposurecomparison of measurements at forehead and wrist
Sleep Research
Seasonal variation in human illumination exposure at two different latitudes
J Biol Rhythms
Exposure to bright light and darkness to treat physiologic maladaptation to night work
Scand J Work Environ Health
Sleep in the laboratory and sleep at homecomparisons of older insomniacs and normal sleepers
Sleep
The Gallup Study of Sleeping Habits
Sleep in America
Sleep In America
Omnibus Sleep in America Poll (sponsored by NSF)
Effects of bright light on mood in normal elderly women
Arch Gen Psychiatry
Reverse first night effect in insomnia
Sleep
Empirical noteself-report versus recorded sleep in healthy seniors
Sleep
Rest-activity and illumination in womeninfluences of age, race, time standard, and season
Sleep
Circadian rest-activity rhythm in different age group as determined by actigraphy
Sleep Res
Gender differences in rest-activity patterns and sleepiness
Sleep Res
Therapeutic effects of bright light in depressed patients
Ann NY Acad Sci
Prevalence of sleep disordered breathing in ages 40–64 yearsa population-based survey
Sleep
Adult illumination exposures and some correlations with symptoms
Short and long sleep and sleeping pills. Is increased mortality associated?
Arch Gen Psychiatry
Cited by (166)
Health disparities and insomnia: Insomnia and physical health: the role of health disparities in defining risk
2023, Encyclopedia of Sleep and Circadian Rhythms: Volume 1-6, Second EditionThe impact of social networks on sleep among a cohort of college students
2021, SSM - Population HealthTime use: The role of sleep
2020, Transportation Research Part A: Policy and PracticeCitation Excerpt :In 2015, the National Sleep Foundation presented recommendations regarding sleep time duration, stating that sufficient sleep duration requirements vary across the lifespan and from person to person, decreasing with age (Hirshkowitz et al., 2015). Also, a U-shaped relationship between sleep duration and age was detected by Groeger et al. (2004), Kronholm et al. (2006) and Szalontai (2006), with the shortest sleep durations observed in the fifth decade of the life span (Jean-Louis et al., 2000). In terms of socioeconomic characteristics, research has found that poor sleep quality has been associated with lower educational qualifications (Hartz et al., 2007; Stewart et al., 2006; Gilles et al., 2005; Kietjna et al., 2003; Moore et al., 2002), unemployment (Hartz et al., 2007; Paine et al., 2004; Rocha et al., 2002) and low income (Hartz et al., 2007; Lauderdale et al., 2006; Hall et al., 1999).
Impact of Sleep Restriction on Food Intake and Food Choice
2020, Neurological Modulation of Sleep: Mechanisms and Function of Sleep Health25-Hydroxyvitamin D status, light exposure and sleep quality in UK dwelling South Asian and Caucasian postmenopausal women
2019, Journal of Steroid Biochemistry and Molecular Biology