Insomnia, also known as sleeplessness, is a sleep disorder where people have trouble sleepingInsomnia is also known as sleeplessness, is a sleep disorder where people have trouble sleeping. They may have difficulty falling asleep, or staying asleep as long as desired. Insomnia is typically followed by daytime sleepiness, low energy, irritability, and a depressed mood. Insomnia can be short term, lasting for days or weeks, or long term, lasting more than a month.
About Normal Sleep
An average person spends about one third of his life sleeping. Normally people (adults) require about 7-9 hours of sound sleep to function well but some people can do very well even with 4-5 hours of sleep.
Infants require much more sleep as compared to adults and they can sleep for up to 18 hours a day (average between 16- 20 hours). By the time they are 3-6 months old they require about 15 hours of sleep. Children older than this require about 10-13 hours of sleep daily. Pre-teens and teenagers require anywhere between 9-10 hours of sleep.
As age advances above 50 years, the sleep duration reduces to about 5 ½ to 6 hours at night.
Normal sleep is of two types:
1. Slow-wave (non-REM) sleep
2. Rapid eye movement (REM) sleep
Slow-wave (non-REM) sleep:
Non-REM sleep lasts about 70-90 minutes. It has four stages as follows:
1. Transitional stage (lasting about 1-7 minutes)
2. Light sleep
3. Moderately deep sleep (about 20 min after falling asleep)
4. Deep sleep
Rapid eye movement (REM) sleep:
- This is a very important stage of sleep
- It usually occurs within 50-90 minutes of falling asleep
- Initially lasts 5-10 minutes; gradually this stage lengthens until the final REM period lasts 50 minutes
- Most dreaming occurs during this phase of sleep
- The eyeballs of a sleeping person will make rapid side-to-side movements under the lids during REM sleep
- The muscles of the body are very relaxed during this phase of sleep
- REM sleep is particularly useful for growth and repair of the brain itself, while the non-REM sleep is useful for repair of the rest of the body