To sleep or not to sleep - Growing older and Sleep

Sleep gradually changes as the individual gets older. New born babies sleep 16h out of 24h, by the time the child has reached the age of 12 is approx 8h, adults sleep 7h and older adults can sleep about 6h. The deepest stage of sleep (Stage 4) may disappear in older adults. The figure below illustrates how sleep changes as the indvidual ages.

Figure 1. Changes in Sleep as the indivual ages. (Souce: Parkes, JD. Sleep and its Disoders (1985) WB. Saunders Company: England, page 20).

Babies and Infants

A regular sleep pattern is established in the human foetus at 30-32 weeks. By 4 months the proportion of 'active' sleep starts to decrease and the 'quiet' sleep increases. Babies and young children show a clear distinction between REM and NREM sleep.

Children

By age 1, children spend 12-13 hours out of 24 hour asleep by the time they reach adolescence it decreases to 8 out of 24 hours.

Adults and Elderly

As the individual becomes older, sleep becomes poor. There is an increase in the number of awakening during the night and also a lengthening of the period spent entering sleep. Most adults sleep between 7 and 9 hours a day, however in older adults not all of this sleep is done at night. An afternoon nap or a nap in front of the TV contributes to the total sleep need for the day. Naps are usually about 30min, by the time the person is 80 the naps can last up to 60mins. Surprisingly older adults wake resfreshed after their night's sleep. If a person wakes up unrefreshed and is experiencing daytime somnolence, he/she should consult a doctor.

Another important change that occurs as the person gets older is an increase in time of falling sleep. There are many factors that may contribute to this, some include medical (medication) or psychological (stress) or simply the body is not ready to go to sleep. As the individual ages the body secretes less melatonin (sleep promoting hormone), therefore the need to go to sleep is not so strong the older the person gets. The reduced amount of melatonin is also responsible for the increased number of awakening during the night.

Medical conditions such as Parkinson's disease, bladder incontinence, arthritis, heart disease, reflux, and respiratory conditions such as asthma and emphysema can also affect sleep.

Interesting information....
	In 1976 a 70 year old lady was reported to sleep an average of 67 minutes every 24 hours without any indication of tiredness!