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

Abstract

The objective of this narrative review paper is to discuss about sleep duration needed across the lifespan. Sleep duration varies widely across the lifespan and shows an inverse relationship with age. Sleep duration recommendations issued by public health authorities are important for surveillance and help to inform the population of interventions, policies, and healthy sleep behaviors. However, the ideal amount of sleep required each night can vary between different individuals due to genetic factors and other reasons, and it is important to adapt our recommendations on a case-by-case basis. Sleep duration recommendations (public health approach) are well suited to provide guidance at the population-level standpoint, while advice at the individual level (eg, in clinic) should be individualized to the reality of each person. A generally valid assumption is that individuals obtain the right amount of sleep if they wake up feeling well rested and perform well during the day. Beyond sleep quantity, other important sleep characteristics should be considered such as sleep quality and sleep timing (bedtime and wake-up time). In conclusion, the important inter-individual variability in sleep needs across the life cycle implies that there is no "magic number" for the ideal duration of sleep. However, it is important 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 exercise in the package for good health.

Keywords: guidelines; life cycle; population heath; public health; recommendations; sleep.

Figure 1

Normal self-reported sleep durations in children aged 0–12 years. Note: The mean reference values are from a meta-analysis of 34 studies from 18 countries. Abbreviations: m, months; y, years.

Figure 2

Normal actigraphy-determined sleep duration values in children aged 3–18 years. Note: The mean reference values are from a meta-analysis of 79 studies from 17 countries.

Figure 3

Sleep duration estimates of Canadians (dashed line) compared with the sleep duration recommendation ranges (solid lines). Notes: Sleep duration estimates for the Canadian population have been recently published.– However, they are not available for newborns, infants, or toddlers. Canadians sleeping less than recommended for optimal health is estimated at 16% for preschoolers, 20% for school-aged children, 30% for teenagers, 32% for adults, and 31% for older adults.