Sleep and Sleeping Disorders 

 Sleep is a time when the body undergoes important restorative processes, growth hormone is released during slow wave delta sleep, and the activities and stresses of the day are processed. Sleep deprivation for as short as one night can cause a decrease in functioning, whereas, prolonged sleep deprivation such as reducing sleep from eight hours to four over a longer period, results in changes to glucose tolerance and overall endocrine function.Sleep and Obesity

Sleeping disorders or disturbances in the sleep wake cycle assume a similar pattern in every culture, although the disturbance in the sleep wake cycle may have different manifestations. Sleep and wakefulness in humans follows a twenty four hour  circadian rhythm.
Stage 1 between waking and sleep lasts no more than ten minutes, breathing is regular, pulse is even, and eyes are closed.
Stage 2 the sleep is very light, however the subject becomes more difficult to awaken, there may be some dream fragments.
Stage 3 the subject slips into a fairly deep sleep, body completely relaxed, body temperature and blood pressure begin to fall.
Stage 4 the subject is in a deep sleep, and much more difficult to awaken.
This cycle repeats thoroughout the sleep period.

Sleep latency may be one expression of a sleeping disorder , the latency period before sleep onset may be a number of hours, so the actual sleep time is considerably reduced. If this sleep disturbance is experienced on a regular basis it may seriously disrupt health, work and social activities.Elderly people may suffer from  sleep latency, often because they may tend to have a number of naps during the course of the day, go to bed too early, and consequently have trouble getting off to sleep.Sleeping Problems in the Elderly

Jet travel across different time zones disrupts the circadian rhythm and causes sleep disturbances, as does shift work. The period of adaptation for shift workers  to adjust to the new time table takes a couple of weeks, however, if the shifts are constantly changed, then the circadian rhythm is in a constant state of disruption, health may suffer as a result of this. High altitudes may cause sleep disturbances in some people, altitudes above 4000 metres usually cause sleep disturbance to most people.Some of these sleep disturbances may be classed as transient, whereas others such as occurs in shift workers are classed as a persistent sleep disturbance.

Poor sleep hygiene may account for a number of sleep disturbances. Going to bed too late, or going to bed at irregular times, eating heavy meals before sleep, exercising too close to bed time, caffeine or alcohol before sleep, and taking the worries of the day to bed with you.

Read more:Sleep Disorders and Serotonin Deficiency