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. Author manuscript; available in PMC: 2021 Sep 1.
Published in final edited form as: Curr Sleep Med Rep. 2020 Jul 25;6(3):129–135. doi: 10.1007/s40675-020-00183-x

Napping in Older Adults: A Review of Current Literature

Zeyu Zhang 1,2, Xueling Xiao 1,3, Weixia Ma 1,4, Junxin Li 1,*
PMCID: PMC7992388  NIHMSID: NIHMS1614980  PMID: 33777656

Abstract

Purpose of Review:

Daytime napping—frequently reported among older populations—has attracted increasing attention in geriatric research due to its association with multiple health conditions. This review aims to integrate the latest knowledge about napping in older adults to provide implications for future research.

Recent Findings:

The prevalence of napping in older adults ranges from 20% to 60% in different studies, but has been consistently reported to be higher than in other age groups. Age-related changes in circadian rhythm and sleep patterns, cultural beliefs, chronic conditions, medications, and lifestyle changes contribute to the high prevalence of napping in older adults. Daytime napping has been associated with multiple health conditions in older adults. Naps of short duration (e.g., 30 minutes) are reported in adults with better health; naps with longer durations (e.g., >90 minutes) have been linked to adverse cardiovascular and diabetes outcomes, declining cognitive function, and increased mortality. Current evidence in the literature, however, is not enough for us to determine the exact role of napping in the health of older adults.

Summary:

Longitudinal and interventional studies are needed to investigate the influence of napping and the critical parameters such as duration, timing, and frequency on health in older adults and the underlying mechanisms. A combination of objective and self-reported measurements of napping are recommended instead of self-reported data only.

Keywords: Daytime Napping, Health, Older Adults

Introduction

Daytime napping has been linked to multiple health outcomes in older adults such as nocturnal sleep, cardiovascular and cognitive health [13]. Daytime napping attracts growing attention in geriatric research as a modifiable behavioral factor that impacts health. Daytime napping is more frequently reported in older adults than in young and middle-aged adults. Changes in sleep patterns, circadian rhythms, and lifestyles in older life make older adults more prone to taking naps during the daytime [4]. Older adults also take naps to counter excessive sleepiness and fatigue from comorbidities or medications [5]. The features of daytime napping are important determinants of health in older adults. This paper provides a general review on daytime napping and its association with health in older adults and its implications for future research.

Prevalence of Daytime Napping in Older Adults

Napping is common in many countries such as China and Latin America [3 6]. The prevalence of napping varies considerably by age. Approximately 50%−80% of children three years of age routinely take daytime naps but only 9% of children over 5 years of age report daytime naps [7]. Interestingly, the prevalence of daytime napping increases to 40% in 14–19-year-old teenagers [8], which may be contributable to the increasing needs of sleep in adolescents and the inadequate sleep opportunity at night. In a Japanese nationwide survey, 41.7% of young populations (20–39 years old) and 45.6% of middle-aged populations (40–59 years old) reported taking naps occasionally (at least one nap per week). Only 11.7% of young and 14.4% of middle-aged adults reported regular naps (more than 4 times a week) [9].

Napping is more prevalent in older adults than in younger populations. Research has reported that the prevalence of napping in older adults ranges from 20% to 60% worldwide depending on the participants’ demographics, definitions of napping, and where the study was conducted [1012]. Afternoon napping is less common in countries with cooler climates and more common in many countries such as Latin America, Asia, and Africa where the temperature increases considerably due to the heat of the afternoon sun. Afternoon napping is usually culturally believed to be a healthy lifestyle in countries where napping is a common practice, particularly in China [10]. For example, Chinese national representative studies report that over 50% of middle-aged and 55% of older adults routinely take an afternoon nap [6 11 12].

In a Korean Genome Epidemiology Study (N=5,427), 35.7% to 42.3% of middle to old-aged (40–69 years) individuals reported regular daytime napping [13]. A population-based study in Japan reported that 21.2% of men and 17.1% of women aged 20 and above reported regular daytime naps (≥4 days/week): 11.7% among young adults (20–39 years old), 14.4% in the middle-age group (40–59 years old), and 25.8% in older adults (older than 60) [9]. In Western countries, daytime napping is also more common in older adults than in other age groups. For example, the National Institutes of Health-AAPR Diet and Health Study reported that 40.3%−52.5% of Americans aged 50–71 take daytime naps [14]. Similarly, Leng and colleagues [15] reported in the European Prospective Investigation into Cancer in Norfolk (EPIC) cohort study that the prevalence of daytime napping was 44% in older adults, which was higher than the 28.6% in the overall sample (13,465 adults).

Timing, Frequency and Duration of Napping

As explained by the circadian sleep-wake regulation mechanisms, mid-afternoon sleepiness peaks at about 14:00 pm [16]. Studies support that people are more likely to take a nap after lunch and usually regard the post-lunch period as an ideal time for a nap [8 12]. Older adults could possibly fall asleep anytime of the day due to the weakened circadian rhythm and homeostatic sleep drive with aging. A study also reported that older adults tend to nap in the early evening due to the age-related advanced circadian rhythms [5].

The frequency of napping in older adults is higher than in younger age groups. In Japan, the proportion who napped seven days per week was higher among adults aged 60 years or older [9]. The American National Sleep Foundation survey found that 24% of respondents who reported napping 4 to 7 times per week were 75 to 84 years of age; the prevalence was 10% among a 55-to-64-year-old group [17]. Older adults may also take multiple naps each day due to cognitive impairment, excessive daytime sleepiness, boredom, etc., which might be detrimental to their health [18 19]. Experts from the National Sleep Foundation in America concurred that more than 4 naps within 24 hours was an indicator of poor sleep health in older adults [20].

Epidemiological studies have shown that the majority of older nappers (>60%) regularly take naps of moderate length, such as 30–60 minutes or 30–90 minutes [69]. Inconsistent findings were reported in studies on whether older adults take longer naps than other age groups. For example, longer naps were less frequently reported in older age groups in Japan [9], whereas in a Chinese population-based study, an older age group was more likely to take longer naps [12].

Factors Associated with Napping

Age-related changes in rhythms and patterns of sleep

Sleep rhythms and patterns change with aging [5 21]. Older adults have decreased ability to maintain sleep than younger adults, which results in an increased number and duration of nocturnal awakenings and shortened nocturnal sleep duration [5 21]. Sleep in older adults tends to be less consolidated with less deep sleep [5]. These changes in nocturnal sleep could potentially lead to nocturnal sleep deficits in older adults. Older adults are also prone to taking naps during the day to compensate for their nocturnal sleep deficits [4].

In addition, the homeostatic drive to sleep and the circadian rhythms become less robust with age. Older adults tend to have advanced circadian timing and decreased circadian amplitude, which contribute to sleepiness in the early evening and to frequent daytime naps [5].

Cultural Belief about Napping

As mentioned previously, napping is more popular in certain countries due to the culturally believed beneficial impact of daytime napping on health [3 6 22]. For example, taking a nap after lunch is a common habit in China and in some Latin America countries. People in these countries are more likely to take a planned nap or take a nap when they experience daytime sleepiness or fatigue [3 6]. In non-napping countries, however, taking a nap in midday may be regarded as a sign of laziness [23]. People may take extra efforts to fight the sleepiness or tiredness, such as using caffeinated drinks to stay awake during the day.

Daytime sleepiness

Excessive daytime sleepiness includes both an inability to stay alert and awake during the day and a more general feeling of sleepiness [24]. Individuals with excessive daytime sleepiness (EDS) may fall asleep unintentionally or at inappropriate times and locations that are more likely to be less stimulating situations. According to the National Sleep Foundation in Washington, DC, the prevalence of EDS among American populations is roughly 20% [25]. EDS is more prevalent in older adult populations and is usually a signal or symptom of certain diseases. EDS that coexists with other comorbidities such as insomnia, cognitive impairment, Parkinson’s disease, or cardiovascular events are associated with many other complex health outcomes [26].

Health conditions

Older adults with chronic health conditions such as neurological disease, cardiovascular disease, cognitive impairment, immobility, or psychiatric disorders[5 9 27 28] are reported to have a higher prevalence of napping. The associations between napping and health outcomes also vary depending on the feature of napping and napping in different cultural contexts. For example, weight gain has been reported to be associated with more frequent daytime napping, which could be explained by obstructive sleep apnea and poor physical health [29].

Medications

Polypharmacy is a serious concern for older adults’ health. Over a third of older adults routinely take five or more kinds of medications to treat their chronic health conditions [30]. Drowsiness and fatigue, for example, are common side effects of medications that are used to treat medical conditions prevalent in older adults such as allergy, insomnia, anxiety, depression, and hypertension. One cross-sectional study suggested that the half-life and prescribing pattern (using as-needed prescription) of benzodiazepine affect sleep quality [30]. The study reported that as-needed prescription (PRN) use of short-acting benzodiazepine is associated with lower nocturnal sleep quality and longer daytime napping compared to the regular use of long-lasting benzodiazepines [31]. Z-drugs such as Zolpidem, Zopiclone and Zaleplon, and antidepressants were also reported to cause sedation and EDS as side effects [32].

Lifestyle factors—retirement style, lack of social interaction, lack of physical activity

Age-related lifestyle changes could also contribute to changes in sleep patterns and to increased daytime napping. After retirement, older adults have more leisure time, which may result in changes of daytime structure as well as regular sleep patterns such as more frequent daytime napping. Studies have reported increasing sleep duration after retirement among older adults [9]. Meanwhile, mental and physical fatigue also decrease after retirement, accompanied by improved self-rated health [33]. The possible justification for these outcomes could be the removal of work stress following the transition into retirement [34].

Social interactions are also considered to be indicators of daytime napping. Evidence from a study in nursing home older adults supported that sleep disturbances and lack of activities negatively influence each other. Individuals in nursing homes suffer from circadian rhythm disorder and non-restful sleep that are significantly associated with impaired communication and low levels of social engagement and activity [35]. Lonely community dwellers are more likely to report sleep fragmentation than those who report more connection to others, suggesting that the feeling of a secure social environment is crucial to better sleep quality [36]. Experiencing daytime sleepiness is considered a risk factor of poor social engagement; however, the bidirectional influence was not evaluated in this study [37]. Further studies should focus more on the effect of social isolation on daytime napping.

Daytime Napping and Health Outcomes in Older Adults

In this section, we review recent studies on daytime napping and multiple health outcomes in older adults, including nocturnal sleep duration, cardiovascular health, diabetes, cognitive function, and all-cause mortality.

Nocturnal sleep duration

Theoretically, short nighttime sleepers are more likely to take daytime naps since napping is a way to compensate for insufficient nocturnal sleep. It is also possible that medical conditions cause both long sleep duration and excessive daytime sleepiness that lead to napping; however, we are not able to draw consistent conclusions from the literature [38]. A review suggested that midday naps were supplemental for lack of nighttime sleep and potentially improved daytime function [18]. Conversely, two Chinese studies, which extracted data from the China Health and Retirement Longitudinal Study, found that self-reported longer post-lunch napping was associated with longer nighttime sleep duration in Chinese older adults [11 12]. This discrepancy might be a result of the variable cultural belief of napping in the sample participants. More importantly, it may reflect that sleep continuity rather than the nocturnal sleep duration is a more important indicator than sleep duration for sleep health in older adults. Sleep efficiency at nighttime, however, was not reported in any of these studies. Future studies should examine the association between daytime napping and nocturnal sleep (duration and efficiency) to explore whether daytime napping is related to nighttime sleep deficits.

Napping and cardiovascular health

In this section, we review recent studies on napping and cardiovascular health including heart rate variability, hypertension, and cardiovascular mortality. In recent studies, napping has been associated with hypertension risk. For example, a meta-analysis [39] suggested a significant association between daytime napping (nap vs. no-nap) and hypertension. However, the majority of studies included in the meta-analysis neither adjusted for nighttime sleep nor specified the circadian timing of napping. A recent population-based study found significant associations between self-reported afternoon napping duration and hypertension, and the associations varied by sex and age. Specifically, longer afternoon napping (≥90 mins) was associated with hypertension, especially in women and older adults [10]. Another study reported decreased risk of hypertension in middle-aged and older adults (>45 years of age) who self-reported habitual daytime napping. Interestingly, the relationship was stronger in those who had a sufficient amount of nocturnal sleep (7–8 hours/night) [40]. The details of habitual napping, such as duration, frequency, or timing, however, were not reported in this study. These studies underscored the importance of taking nocturnal sleep and gender differences into consideration when exploring the relationship between hypertension risks and napping among older adults.

Reduced heart rate variability (HRV) has been associated with numerous adverse health outcomes such as diabetes, cardiovascular diseases, inflammation and psychiatric diseases [41]. Nakayama et al. found that napping was associated with increased HRV among older adults with cardiovascular diseases [42]. Nappers had significantly higher HRV than non-nappers during wakefulness, sleep, and one hour after the beginning of the nocturnal sleep period.

Inconsistent findings were reported regarding napping and cardiovascular risks. For example, a study of a sample in 1,722 older males (71 to 92 years of age ) without a history of heart attack or heart failure found that self-reported napping over an hour was associated with higher levels of cardiovascular risk biomarkers in peripheral blood, such as raised N-terminal pro-brain natriuretic peptide, mean troponin levels, and reduced lung function [43]. However, another study in a sample of 23,681 healthy older adults (without chronic heart disease, stroke or cancer at baseline) found that napping was associated with lower cardiovascular mortality after 6 years, no matter the duration and frequency of napping [42].

There is no doubt that napping is associated with cardiovascular health but the direction of the relationships from the evidence is unclear. The relationship between napping and cardiovascular disease in older adults should be taken cautiously since the relationship may be confounded by older adults’ preexisting physical conditions.

Napping and diabetes

Longer daytime naps have been associated with increased risk of diabetes among older adults. A study in older adults with metabolic syndrome found a significantly positive relationship between napping more than 90 minutes (as assessed by accelerometer) and the prevalence of type 2 diabetes, and also a positive association between napping longer than half an hour and BMI/waist circumference (WC) [44]. Consistent with these findings, both self-reported and actigraphy-measured objective nappers had a higher incidence of diabetes [45], and the relationship remained after adjusting for age, sex, education, lifestyle, physical status, BMI, and WC [15]. In addition, a longitudinal study revealed that individuals with both sleep duration ≥ 10 h and napping > 60 min had a 72% higher risk of incident diabetes at 11 years follow-up than those with sleeping 7~<8 h and napping 0 min[46]; however, this relationship between self-reported after-lunch napping and the prevalence of diabetes was not significant among older postmenopausal women [47].

Napping and cognitive function

A possible U-shaped association between napping and cognitive functions in older adults was suggested in some studies where a certain duration of afternoon nap was associated with improved cognitive outcomes [11 48]; however, other studies suggested that longer naps may be associated with cognitive decline and dementia in older adults [49 50]. For example, a longitudinal study found that self-reported napping at baseline was associated with less decline in cognition function after 10 years [51]. Studies in Chinese older adults found that self-reported non-napping or long napping (>90 minutes) were associated with more cognitive decline in two years and that naps of a moderate duration were associated with better cognition [11 48]. Another American nationally representative study among an older population indicated that long duration (> 60 minutes) nappers had worse performance of cognitive tests. Among participants undiagnosed with dementia or proxies, moderate-duration naps (31–60 minutes) were associated with better delayed word recall (DWR) than short naps (≤ 30 minutes). In addition, unintentional nappers were poorer in word recall test performance than non-nappers and intentional nappers; non-nappers reported better self-rated memory than frequent nappers [52]. More frequent napping per week was also related to amyloid deposition [53], a molecule involved in Alzheimer’s disease. To conclude, for older adults, napping may be associated with cognitive function; more research is urgently needed to decide the exact napping patterns that could contribute to cognitive maintenance.

Napping and all-cause mortality

Significant relationships between daytime napping and mortality in older adults were identified in the literature. Specifically, longer nap durations were consistently associated with increased mortality across studies with 10-years follow-up on average [5456]; however, the heterogeneity of the samples and the confounders adjusted in the models across the studies limited our ability to draw conclusions from these studies. A meta-analysis [39] suggested that older adults who regularly napped for more than 30 minutes had 27% increased all-cause mortality risk compared to those who reported no naps. A 13-year follow-up study with a 16,374 middle to older-aged sample [22] drew a similar conclusion that napping contributed to increased risk of all-cause mortality compared with those having no nap, after controlling for confounders such as demographics, socioeconomic status, lifestyle (physical activity, and alcohol and cigarette use), depression, general health, and previous illnesses; the Harazd Ratio equaled 1.14 (95% CI = [1.02,1.27]) when comparing those napping less than 1 hour with non-nappers, and that was 1.32 (95% CI = [1.04,1.68]) for those napping more than 1 hour.

In summary, most studies reviewed in this section were observational studies with relatively large sample sizes. We could not draw any causal associations between daytime napping and health outcomes from these analyses, and there is the possibility that relationships between napping and mortality are bidirectional. In addition, most of the studies used a self-reported measure of napping, which may introduce recall bias and lead to incorrect results. A few studies objectively assessed napping using actigraphy, which may overestimate napping duration and introduce bias to results as well. More importantly, most studies only assessed one feature of napping (duration or frequency) rather than considering all relevant napping parameters. Future studies on napping and health in older adults need to systematically assess features of daytime napping using both subjective and objective measures.

Conclusions

Daytime napping—which is reported to be more frequent in school-aged children and older adults—can occur in all age groups. Older adults are more likely to take naps during the daytime due to age-related changes in circadian rhythms and sleep patterns. Cultural beliefs, chronic conditions, medications, and lifestyle changes can also contribute to daytime napping. Napping may impact health outcomes among older people. Longer nap durations have been linked in observational studies with adverse health outcomes such as cognitive decline, increased cardiovascular and mortality risks; however, current evidence in the literature is not enough for us to determine the exact role of napping in older adults’ health. To date, the mechanisms of how and why health outcomes are impacted by napping have not been well studied and need to be investigated in future research. Longitudinal and interventional studies are critically needed to investigate the influence of napping and the underlying mechanisms on health in older adults.

Footnotes

Human and Animal Rights

This article does not contain any studies with human or animal subjects performed by any of the authors.

Conflicts of interest

All authors declare that there are no conflicts of interest relavent to the article.

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