Sleeping hours: what is the ideal number and how does age impact this?

The full terms of this license are available at hypertext transfer protocol : //www.dovepress.com/terms.php and incorporate the creative Commons Attribution – Non Commercial ( unported, v3.0 ) License ( hypertext transfer protocol : //creativecommons.org/licenses/by-nc/3.0/ ). By accessing the workplace you hereby accept the Terms. Non-commercial uses of the work are permitted without any promote permission from Dove Medical Press Limited, provided the work is by rights attributed. The objective of this narrative review paper is to discuss about sleep duration needed across the life. sleep duration varies widely across the life and shows an inverse relationship with senesce. rest duration recommendations issued by public health authorities are authoritative for surveillance and assistant to inform the population of interventions, policies, and healthy sleep behaviors. however, the ideal measure of rest required each nox can vary between different individuals due to genic factors and other reasons, and it is crucial to adapt our recommendations on a individual basis. Sleep duration recommendations ( public health approach ) are well suited to provide steering at the population-level point of view, while advice at the individual flat ( eg, in clinic ) should be individualized to the world of each person. A broadly valid assumption is that individuals obtain the right amount of sleep if they wake up feeling good rested and perform well during the day. Beyond rest measure, other significant sleep characteristics should be considered such as sleep quality and rest time ( bedtime and wake-up clock ). In decision, the crucial inter-individual variability in sleep needs across the life cycle implies that there is no “ magic phone number ” for the ideal duration of sleep. however, it is authoritative to continue to promote sleep health for all. Sleep is not a waste of time and should receive the same level of attention as nutrition and practice in the package for commodity health .

Introduction

Sleep is increasingly recognized as a critical part of goodly exploitation and overall health. 1 – 3 Healthy rest comprises many dimensions, including adequate duration, good quality, appropriate timing, and the absence of sleep disorders. 4, 5 not getting adequate rest at night is broadly associated with day sleepiness, day tire, depressed climate, poor day functioning, and other health and safety problems. 6 – 9 Chronic insufficient rest has become a business in many countries, given its association with morbidity and mortality. 10, 11 For case, accustomed short sleep duration has been associated with adverse health outcomes including fleshiness, 12 type 2 diabetes, 13 high blood pressure, 14 cardiovascular disease, 15 depression, 16 and all-cause deathrate. 17 sake in finding ways to improve sleep patterns of individuals at the population-level point of view is growing, and experts recommend that sleep should be considered more seriously by public health bodies, internet explorer, given as much attention and resources as nutrition and forcible activeness. 18 – 20 Guidelines on the recommend come of sleep needed for optimum health exist ; they are a vital joyride for surveillance, they help inform policies, they can provide a starting point for intervention strategies, and they educate the general public about healthy sleep behaviors. however, sleep needs may vary from one person to another at any given age across the life. Additionally, some age groups and populations are more probably to report insufficient sleep duration and may be at greater risk for damaging health outcomes. 5, 6, 11 The objective of this narrative review article is to discuss whether or not an ideal amount of sleep exists for optimum health and how it is impacted by age.

Insufficient sleep across the lifespan

insufficient sleep has become far-flung over the last decades, specially among adolescents. 11, 21 Both physiological factors and exogenous exposures come into play in explaining insufficient sleep in this age group. Sleep retrenchment is often attributed to extrinsic factors, such as artificial lightly, caffeine use, miss of physical natural process, no bedtime rules in the family, and the increase handiness of information and communication technologies. 22 – 25 In adolescence, insufficient sleep has besides been attributed to intrinsic factors such as pubertal hormonal changes, which is associated with a lurch toward an evening chronotype 26 that may besides lead to an asynchronism between the biological clock, characterized by a phase check, and the social clock. 27 In adolescents, this biological phase delay combined with the social clock, for which the independent synchroscope is the situate and early school begin time, contributes to the watch sleep deficits in this population. 27 The conflict between intrinsic and extrinsic factors, biological time and social time, has been indicated to be greater during adolescence than at any other charge in our lives. 28 Despite some overlap between factors that could explain insufficient sleep among adolescents and adults, such as exposure to artificial light at night, miss of physical bodily process, caffeine consumption, and inadequate sleep hygiene, other factors that could specifically be related to insufficient rest among adults may include but not be limited to work demands, social commitments, health and/or affectional problems, and family dynamics ( eg, working mothers and children with wide agendas ). 10 In the aged, sleep patterns and distribution undergoes meaning quantitative and qualitative changes. Older adults tend to have a harder time falling asleep and more trouble staying asleep. This period of life is much accompanied by a circadian shift to a dawn chronotype, as opposed to the evening chronotype change during adolescence, that results in early bedtime and risetime. 29 Research suggests that the need for sleep may not change with senesce, but it is the ability to get the necessitate sleep that decreases with age. 10 This decreased ability to sleep in older adults is often secondary to their comorbidities and refer medications ( polypharmacy ) quite than convention aging processes per southeast. 30 – 32 furthermore, the increase frequency of sleep-related disorders in the aged population lend to a lot of the sleep deficiencies observed in this population. 33 – 36 Inadequate sleep in the aged could besides be related to early factors, such as life changes ( eg, retirement, physical inaction, decreased sociable interactions ), age-related changes in metamorphosis, and environmental changes ( eg, placement in a nurse home ). 37 A systematic review and meta-analysis reported that in the aged population both short and retentive sleep are independently associated with increase risk of cardiovascular-related and cancer-related mortality. 38 additionally, adjustments for health conditions in the studies examining the association between sleep duration and deathrate risks did not attenuate the forte of the association between farseeing rest and increased gamble of mortality, which suggests that the mechanisms in these associations may differ between long sleep and short rest duration. 38 One potential explanation for this association, between long sleep duration and increased risk of non-communicable diseases relate mortality, may be related to the increased prevalence of sleep fragmentation in this population. 38, 39 While older adults may report long sleep duration, early sleep characteristics, namely sleep computer architecture and quality, are altered by sleep atomization. As the relationship between long sleep duration and increased risk of cardiovascular-related and cancer-related deathrate is singular to the aged population, the causality should be far investigated .

Normative sleep duration values across the lifespan

Sleep–wake regulation and sleep states evolve identical quickly during the first year of life. 40 For case, newborns ( 0–3 months ) do not have an established circadian rhythm and therefore their sleep is distributed across the wide 24-hour day. 41 At 10–12 weeks, the circadian rhythm emerges and sleep becomes more nocturnal between ages 4 and 12 months. 42 Children continue to take day naps between 1 and 4 years of age, and nox wakings are coarse. 43 Daytime naps typically stop by the old age of 5 years and nightlong sleep duration gradually declines throughout childhood, in part ascribable to a shift to belated bedtimes and unaltered wake up times. 43 sleep patterns are explained by a complex interplay between genic, behavioral, environmental, and social factors. Examples of factors that can determine sleep duration include daycare/school schedules, parenting practices, cultural preferences, family routines, and individual differences in genetic makeup. Despite inter-individual differences in sleep duration, external prescriptive data exist to show the normal distribution of rest duration for unlike senesce groups. however, it is crucial to keep in mind that prescriptive mention values by no means indicate anything about what the ideal or optimum sleep duration should be, ie, the amount of rest associated with health benefits. however, they tell us about what is normal ( or not ) in the population and provide a valuable yardstick for practitioners and educators when dealing with sleep-related issues. A meta-analysis by Galland et aluminum 44 examined the scientific literature with regards to normal sleep patterns in infants and children aged 0–12 years. The review included 69,542 participants from 18 countries and immanent measures were used to determine sleep duration ( sleep diary or questionnaire ). They calculated average address values and ranges ( ±1.96 SD ) for sleep duration of 12.7 h/day ( 9.0–13.3 ) for infants ( < 2 years ), 11.9 h/day ( 9.9–13.8 ) for toddlers/preschoolers ( ages 2–5 years ), and 9.2 h/day ( 7.6–10.8 ) for children ( 6–12 years ). normative rest duration data across senesce categories are shown in. A strong inverse kinship with age was discernible from these data, with the fastest rate of descent observed over the first 6 months of life ( 10.5 min/month refuse in rest duration ). The review besides highlighted that Asians had significantly shorter sleep ( 1 hour less over the 0–12-year range ) compared to Caucasians or early ethnic groups. overall, these reference point values should be considered as global norms because the authors combined different countries and cultures .An external file that holds a picture, illustration, etc.
Object name is nss-10-421Fig1.jpgOpen in a separate window Galland et alabama 45 besides reported in 2018 prescriptive sleep duration values for children aged 3–18 years as measured with actigraphy ( objective judgment of sleep duration ). Their meta-analysis included 79 articles and involved children from 17 countries. As shown in, pooled mean estimates for nightlong sleep duration declined from 9.68 hours ( 3–5 years age band ) to 8.98 hours ( 6–8 years age band ), 8.85 hours ( 9–11 years long time band ), 8.05 hours ( 12–14 years historic period band ), and 7.4 hours ( 15–18 years age band ). These prescriptive sleep duration values may aid in the interpretation of actigraphy measures from night recordings in the pediatric population for any given historic period .An external file that holds a picture, illustration, etc.
Object name is nss-10-421Fig2.jpgOpen in a separate window A meta-analysis of objectively assessed sleep from childhood to adulthood was besides published by Ohayon et alabama 46 in 2004 to determine normative sleep values across the life. A full of 65 studies representing 3,577 goodly individuals aged 5–102 years were included. Polysomnography or actigraphy was used to assess sleep duration in the include studies. They observed that sum sleep time importantly decreased with historic period in adults, while it was the lawsuit in children and adolescents only in studies performed on school days. This form suggests that, in children and adolescents, the decrease in total sleep time is not related to growth but to other factors such as earlier school depart times.

In drumhead, normative rest duration values are helpful in providing information on what constitutes the norm for a given senesce and what is considered outside the average. These address values are impacted by the method acting used to determine sleep duration ( objective v subjective assessment ) and provide norms at the population-level point of view. many factors can determine sleep duration at the individual grade. Although international prescriptive data provide information about the normal distribution of sleep duration in the population, they do not identify the duration associated with health benefits. For example, having a sleep duration that fits with the average of the population is by no means indicative of either a commodity or a bad rest amount. optimum sleep duration, or the come of sleep associated with favorable outcomes, is what is used for public health recommendations and is discussed in the adjacent section .

Recommended amount of sleep across the lifespan

In 2015, the National Sleep Foundation in the US released their update sleep duration recommendations to make scientifically fathom and practical recommendations for daily sleep duration across the life. 47 The lapp year, the american Academy of Sleep Medicine and the Sleep Research Society released a consensus recommendation for the sum of sleep needed to promote optimum health in adults. 48 The year after, they released their recommend sum of sleep for pediatric populations. 49 Both sleep guidelines issued by the US used a alike developmental approach to deliver their rest duration recommendations, which included a consensus and a vote process with a multidisciplinary expert dialog box. The sleep duration recommendations can be found in .

Table 1

National sleep foundation (US)
AASM/SRS (US)
24-hour movement guidelines (Canada)
Age groupRecommendationAge groupRecommendationAge groupRecommendation
Newborns (0–3 months)14–17 hoursNewborns (0–3 months)Not includedNewborns (0–3 months)14–17 hoursInfants (4–11 months)12–15 hoursInfants (4–11 months)12–16 hoursInfants (4–11 months)12–16 hoursToddlers (1–2 years)11–14 hoursToddlers (1–2 years)11–14 hoursToddlers (1–2 years)11–14 hoursPreschoolers (3–5 years)10–13 hourPreschoolers (3–5 years)10–13 hoursPreschoolers (3–4 years)10–13 hoursChildren (6–13 years)9–11 hoursChildren (6–12 years)9–12 hoursChildren (5–13 years)9–11 hoursTeenagers (14–17 years)8–10 hoursTeenagers (13–17 years)8–10 hoursTeenagers (14–17 years)8–10 hoursYoung adults (18–25 years)7–9 hoursAdults (18–60 years)≥7 hoursAdults (18–64 years)In developmentAdults (26–64 years)7–9 hoursOlder adults (≥65 years)In developmentOlder adults (≥65 years)7–8 hoursOpen in a separate window many organizations around the world have their own sleep duration recommendations, and the target of this article is not to review the different sleep duration guidelines. overall, they are all very alike, and much reference the recommendations from the US. In Canada, full-bodied and evidence-informed sleep guidelines became available in 2016. 50, 51 The sleep recommendations in Canada for children of all ages, besides known as the 24-hour guidelines, are integrated with physical action and sedentary behavior recommendations to cover the stallion 24-hour period ( sleep/wake period ). This allows to put more vehemence on the overall “ cocktail ” of behaviors for a healthier 24-hour day, rather than isolating individual behaviors. This integrate overture to health, with a concentrate on the interrelationships among rest, sedentary behavior, and forcible action, is an authoritative promotion in public health message. It emphasizes that all of these behaviors matter evenly, and balancing all three is required for friendly health outcomes. The canadian 24-hour guidelines were the drift for the growth of exchangeable guidelines in Australia, 52 New Zealand, 53 and the trigger of similar global guidelines by the World Health Organization. Similar integrated 24-hour guidelines for adults and older adults are presently being developed in Canada to cover the entire life. The sleep duration recommendations contained within the 24-hour movement guidelines can be found in. Although sleep duration recommendations are based on the best available testify and technical consensus, they are still largely reliant on experimental studies using self-reported sleep duration. More longitudinal studies and sleep restriction/extension experiments are needed to better quantify the upper and lower limits of healthy sleep duration, and the shape of the dose–response bend with a broad range of health outcomes. current sleep duration recommendations besides suggest that a popularize optimum exists for the stallion population ; however, it is unlikely to be the case and this optimum can vary depending on the health result examined. 54 There is besides inter-individual variability in sleep needs in that sleeping shorter or longer than the recommend amount may not inevitably result in adverse effects on health. For example, genic differences between individuals can explain some of the unevenness in sleep needs. however, intentionally restricting sleep over a prolong period of time ( i, chronic sleep loss ) is not a good mind and can impact health and safety. 47 frankincense, although sleep recommendations are a beneficial instrument for populace health surveillance, they need to be adapted on a individual footing in clinic ( not a one-size-fits-all recommendation ). sleep duration recommendations have ranges, or zones of optimum sleep, suggesting that the kinship between sleep duration and adverse health outcomes is u-shaped, with both extremities, sleep durations that are excessively brusque or besides long, associated with negative effects on health. 47 – 51 There is a large body of evidence providing biological plausibility for short sleep as causally related to a wide rate of adverse health outcomes ; however, the function of long rest is less clear. aside from the aged population, long sleep is generally associated with other health problems ( eg, depression, chronic pain, low socioeconomic status ) that can confound the associations. 55, 56 Reverse causing and residual confuse are thus well mechanisms to explain the associations between long sleep and adverse health outcomes. 55, 56 This may explain why the american Academy of Sleep Medicine and the Sleep Research Society recommends a threshold value for adults ( ≥7 hours per night ) preferably than a image ( eg, 7–9 hours per night ) ( ). however, excessive hanker sleep duration may be enlightening as it can be indicative of poor rest efficiency ( internet explorer, spending a fortune of time in bed but of low quality ). Self-reported sleep duration is typically used in population health surveillance studies, because it provides several advantages ( eg, cheap, not invasive, and logistically slowly to administer to a large sample of individuals ). however, the concession is that sleep duration recommendations are then largely based on self-reported data. It is long-familiar that self-reported sleep duration overestimates actual rest duration. 57 thus, it would be misleading to use an objective measure of sleep duration to report the preponderance of abruptly sleepers in a given sample ; this would result in an overestimate of true shortstop sleepers. The growing popularity of actigraphy and wearable technologies for health behavior tracking in epidemiology is however desirable for providing better sleep estimates and more accurate associations with health outcomes. 58, 59 Sleep duration recommendations are besides probably to evolve over time, as more aim measures of sleep are used in future studies. For example, an individual self-reporting 7 hours of sleep per night may actually get 6 hours if assessed objectively with actigraphy, as it can better account for total sleep by accurately measuring sleep attack and episodes of night wakings. 60 frankincense, using authentic tools for tracking sleep duration over prison term is important, and one must keep in take care that the overall rest duration practice is more critical to long-run health than one snapshot in meter ( internet explorer, chronic effect vs acute effect of insufficient sleep on health ). Consumers have besides become increasingly concerned in using seaworthiness trackers and smartphone applications to assess their sleep. These devices provide information on sleep duration and even sleep quality from in-built accelerometry but the mechanisms and algorithms are propriotery. 61 – 64 The growing body of attest on consumer sleep tracking devices against polysomnography/actigraphy shows that they tend to underestimate sleep disruptions and overestimate sleep duration and rest efficiency in healthy individuals. 61 – 64 Although consumer sleep track devices are changing the landscape of sleep health and have important advantages, more inquiry is needed to better determine their utility and reduce current shortcomings. 61 – 64 population statistics in Canada indicate that 16 % of preschoolers sleep less than recommended, while 20 % of children and one-third of teenagers, adults, and older adults report less-than-recommended sleep durations for optimum health. 65 – 67 These nationally representative surveys use subjective data and are thus comparable to the sleep duration guidelines. As shown in, the average sleep duration of Canadians by age group is situated at the lower edge of the sleep duration recommendations. On average, a big proportion of Canadians meet the sleep duration recommendations ( eg, two-third of teenagers and adults ) ; however, a large number of individuals fail to meet the guidelines ( eg, one-third of teenagers and adults ). If we dig deeper, we realize that the adolescent group has shown the greatest rate of worsen in sleep duration in past decades, specially on school days. 11 Knowing the senesce groups more likely to experience insufficient sleep is critical to help inform the development of interventions aimed at improving sleep ( eg, having educate start times not earlier than 8:30 am for high-school students ). 68 – 70An external file that holds a picture, illustration, etc.
Object name is nss-10-421Fig3.jpgOpen in a separate window

Ideal amount of sleep: fact or fiction?

As discussed in this article, there is no magic number for all in terms of the ideal sleep come to obtain each night. Sleep duration recommendations are meant for public health guidance, but need to be individualized to each patient in the clinic. sleep needs are determined by a building complex fixed of factors, including our familial constitution, environmental and behavioral factors. For exercise, high-performance athletes need more sleep to perform at high grade and recover from their intense physical coach. sleep needs in children and adolescents can besides be driven by their growth stage, autonomous of their chronological senesce. 46 This means that changes in rest patterns may happen earlier ( at a younger senesce ) for some or at an older age for others. objectively, our current evidence of sleep necessitate is based on circadian, homeostatic, and ultradian processes of rest rule and sleep want. The notion of “ optimum sleep ” is complex and ailing understand. 71 The definitions of optimum sleep besides vary in the literature. It is very often defined as the sum recommended by public health authorities. It has besides been defined as the daily sum of sleep that allows an individual to be fully wake up ( i, not sleepy ), and able to sustain normal levels of performance during the day. 72 Others have besides defined it as the sum of sleep required to feel refreshed in the morning. 73 The notion of a new definition to optimal sleep based on performance is of growing interest in the literature. For exemplar, sleep reference interventions have been shown to improve athletic performance. 74, 75

however, as discussed in this article and by other sleep experts, 76 there is no charming number for optimum sleep, and sleep is influenced by inter- and intra-individual factors. similarly, in a context of sleep privation, individual differences in sleep homeostatic and circadian rhythm contributions to neurobehavioral impairments have been elegantly documented by Van Dongen. 77 – 79 optimum sleep should be conceptualized as the sum of sleep needed to optimize outcomes ( eg, performance, cognitive function, genial health, physical health, quality of life sentence, etc ). This implies that there might be many dose–response curves that may differ in shape between outcomes. 54 typically, the peaks of each health result should fall somewhere within the commend sleep duration range. however, the claim total of sleep to get each night for optimizing all relevant health outcomes is not straightforward or omnipresent as the optimum amount for one consequence may not be the like for another consequence ( eg, 9 hours of sleep per nox could be the ideal for athletic performance, while 7 hours could be the best for academic accomplishment ). besides, determining the causal effects of sleep indigence on health is not an easy tax and requires experiments ( eg, interventional study designs with better five reduced sleep, both sharply and chronically applied, and then assessing outcomes on physiology, wellbeing, health, and behavior ). Although the present article focused on sleep duration, many other dimensions of sleep are authoritative beyond getting a sufficient measure each nox. These include aspects of sleep quality such as sleep efficiency ( internet explorer, proportion of the clock time in bed actually asleep ), sleep time ( internet explorer, bedtime/wake-up times ), sleep architecture ( i, sleep stages ), sleep consistency ( i, daily unevenness in rest duration ), sleep consolidation ( i, organization of sleep across the night ), and sleep atonement. For exemplar, the National Sleep Foundation recently released evidence-informed rest quality recommendations for individuals across the life. 80 These included sleep continuity variables such as sleep reaction time, act of awakenings > 5 minutes, wake after sleep attack, and sleep efficiency. Along the lapp lines, monophasic sleep ( i, sleeping once per day, typically at night ) is considered the norm in our company but other sleep patterns ( eg, biphasic or polyphasic ) are besides observed depending on the preference of each person or culture. napping is increasingly seen as a public health creature and countermeasure for sleep loss in terms of reducing accidents and cardiovascular events and improving working operation. 81

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