Our sleep need depends upon genetic and physiological factors and also varies by age, sex, and previous sleep amounts. However, a simple definition of sufficient sleep is a sleep duration that is followed by a spontaneous awakening and leaves one feeling refreshed and alert for the day. Sleep Function and Need Need for sleep is complex because it is bound up with the more general question of the function of sleep. As we do not understand the exact function of sleep, and it is possible that sleep serves many purposes, simple benchmarks for defining adequate sleep are difficult to identify. Normal individuals perceive that sleep is restorative.

The common assumption that population sleep duration has declined in the past few decades has not been supported by recent reviews, which have been limited to self-reported data. The literature was searched for studies published from —, which assessed objective sleep duration TST in healthy normal-sleeping adults. The search found studies that met inclusion criteria, with data points representing 6, individuals ages 18—88 years. Data were assessed by comparing the regression lines of age vs.

Although the amount of sleep you get each day is important, other aspects of your sleep also contribute to your health and well-being. Good sleep quality is also essential. Signs of poor sleep quality include not feeling rested even after getting enough sleep, repeatedly waking up during the night, and experiencing symptoms of sleep disorders such as snoring or gasping for air. Improving sleep quality may be helped by better sleep habits or being diagnosed and treated for any sleep disorder you may have. Skip directly to site content Skip directly to page options Skip directly to A-Z link.

How much sleep do we really need, and what happens if we get too little or too much? We spend about a third of our lives sleeping, so you've asked an important question. The National Sleep Foundation recommends seven to eight hours of sleep for people over age 64 and seven to nine hours for ages 18 to Kids need more sleep. Studies have asked large numbers of people how many hours of sleep they actually average and followed the health of these people over decades.