Sleep is a physiological process wherein some of the systems of the body go into the pause mode while others go in for heightened activity. In short it is not a complete shutdown but a physiologically complex period of time wherein the body systems are rejuvenated and cleansed.
Sleep follows a definitive pattern called the circadian rhythm. This is a biological clock which is controlled by the brain neurons. These neurons respond to light, temperature, hormones and other signals. The body is so programmed that it falls into slumber for a 8 hours period and can remain awake for the remaining time. If this rhythm is disturbed, normal functioning of the body is disturbed. Travel to other countries also disturbs this clock and leads to what is called a jetlag. People travel to other continents, and on landing, sleep for hours together because the system is tuned to go to bed at a certain time, though it may broad daylight at that part of the world. It takes time to adapt to the new day and night schedule.
Sleep is divided into 2 types – the REM( the rapid eye movement) sleep or active sleep and the non R.E.M. (the non rapid eye movement)sleep or the quiet sleep. The later is again divided into different stages. Actually sleep starts with a period of non REM sleep and then moves on to the REM sleep. The body drifts between these two types of sleep 4-6 times in a night time.
The REM sleep is the most restorative part of the sleep cycle. During the REM sleep the brain is at the peak of activity while the whole body is blissfully resting. Dreams are common and the there is rapid movement of the eyes during this time. The non REM sleep has 4 stages. The first stage is light sleep where the person drifts in and out of sleep and can be awakened easily. There is slow movement of the eyes and very little muscle contractions. The second stage is the stage of preparation for deep sleep. During this stage the body temperature drops and the heart rate slows down. Stage 3 is deep sleep and it is marked by extremely slow brain waves called delta waves. Night walking, night terrors, bed wetting etc are common during this time. Parasomnia is the term used to describe these behaviors. They occur during transitions between REM and non REM sleep. Stage 3 and 4 sleep is called deep sleep and the brain records very slow wave pattern. This is the most refreshing part of the sleep cycle and it is very difficult to awaken from this phase of sleep. The body conservés this phase and requires a compensation the following day in case of deficit during one night.
Human Growth hormone is released during the first spell of deep sleep. The brain detoxifies during deep sleep. Between 11 pm and 3 am is the time for heightened activity in the liver. It is of greatest importance that people sleep during this period. People doing night shifts develop a certain behaviour- anger, stress, frustration and resentment . These are attributed to liver malfunction
The commonest sleep disorder is Insomnia. It is marked by an inability to go sleep in the night and may also manifest as getting up much earlier than planned. The causes of insomnia are psychological problems like stress, anxiety and depression, hormonal problems such as hyperthyroidism, disruptions in the circadian rhythm and certain medical problems such as asthma, arthritis, low back pain.
The signs and symptoms of insomnia are inability to fall asleep, waking up in between sleep, waking up before normally scheduled time, tiredness in the morning, falling asleep during the day, lack of concentration in work, anxiety, depression, tension headaches etc.
Insomnia gets better when the underlying cause is removed . In the present day the most important cause of insomnia in the young adult is their job routine that involve long hours of sitting before the computer. Studies tell us that computer work for 5 hours a day most days of the week is an isolated cause of insomnia. This is the scenario where the importance of sleep hygiene cannot be stressed enough.
Sleep hygiene is a term very widely used by the common man to put together a list of habits that nurture good sleep. They start with simple routines like having an early dinner, a small round of simple activity like strolling and chatting about nice things in life, switching off the electronic gadgets, using the bedroom only for sleeping and not as a living room, using good mattresses, maintaining th right temperature, switching off lights and noises and if possible meditating for a few minutes before going to bed. These habits though simple go a long way in getting the required quota of sleep
Otherwise there are sleeping pills, antidepressants, melatonin and other prescription drugs that are widely used. These have to be the last resort when other methods have failed
There is no hard and fast rule for sleep, and there is no right and wrong. 7 to 8 hours of sleep is usually required by everyone. The quality of sleep is reflected in the period of wakefulness and the work done the following day.