Our preferred sleep times and our sleep requirements vary throughout our life cycle. Newborns tend to sleep between 16 and 18 hours per day, preschoolers tend to sleep between 10 and 12 hours per day, school-aged children and teenagers usually prefer at least 9 hours of sleep per night, and most adults say that they require 7 to 8 hours per night (Mercer, Merritt, & Cowell, 1998; National Sleep Foundation, 2008). 1 There are also individual differences in need for sleep. Some people do quite well with fewer than 6 hours of sleep per night, whereas others need 9 hours or more. The most recent study by the National Sleep Foundation suggests that adults should get between 7 and 9 hours of sleep per night (Figure 5.3), and yet Americans now average fewer than 7 hours.
Source: Adapted from National Sleep Foundation. (2008). Sleep in America Poll. Washington, DC: Author. Retrieved from http://www.sleepfoundation.org/sites/default/files/2008%20POLL%20SOF.PDF.
Getting needed rest is difficult in part because school and work schedules still follow the early- to-rise timetable that was set years ago. We tend to stay up late to enjoy activities in the evening but then are forced to get up early to go to work or school. The situation is particularly bad for college students, who are likely to combine a heavy academic schedule with an active social life and who may, in some cases, also work. Getting enough sleep is a luxury that many of us seem to be unable or unwilling to afford, and yet sleeping is one of the most important things we can do for ourselves. Continued over time, a nightly deficit of even only 1 or 2 hours can have a substantial impact on mood and performance.
Sleep has a vital restorative function, and a prolonged lack of sleep results in increased anxiety, diminished performance, and, if severe and extended, may even result in death. Many road accidents involve sleep deprivation, and people who are sleep deprived show decrements in driving performance similar to those who have ingested alcohol (Hack, Choi, Vijayapalan, Davies, & Stradling, 2001; Williamson & Feyer, 2000). 2 Poor treatment by doctors (Smith-Coggins, Rosekind, Hurd, & Buccino, 1994) 3 and a variety of industrial accidents have also been traced in part to the effects of sleep deprivation.
Good sleep is also important to our health and longevity. It is no surprise that we sleep more when we are sick, because sleep works to fight infection. Sleep deprivation suppresses immune responses that fight off infection, and can lead to obesity, hypertension, and memory impairment (Ferrie et al., 2007; Kushida, 2005). 4 Sleeping well can even save our lives. Dew et al. (2003) 5 found that older adults who had better sleep patterns also lived longer.
Source: Adapted from Ross, J. J. (1965). Neurological findings after prolonged sleep deprivation. Archives of Neurology, 12, 399–403.