The reason is the same as why we eat. Sleep is a basic human need. It is the process for the body to build new tissue, repair damaged cells and release of growth hormone. In short, we need sleep to heal and recharge our body.

How much sleep is enough?

The answer depends very much on the person. In general, An adult needs an average of 8 to 8.5 hours of sleep each night. Most newborns babies have 16 - 18 hours of sleep. While pre-schools childrens sleep 10 - 12 hours a day.

Teens require at least 9 hours of sleep a day

What will happen to me when I have sleep deprivation?

Sleep deprivation affects you physically and mentally. Your mood will be affected. You will likely to feel depressed or sadden and at time a sense of hopelessness and mild paranoia. Moltivation will often go low and you refuse to attend even a simple task. It is not that you are unable to do the task but your interest of doing it is gone.

Your vision system is afftected too. You may make errors in judging depth or distance and see blurred or double image while reading.Sleep deprivation also causes bad memory. You are not able to remember recent events and you face more difficulty in learning.

Physically you are more sensitive to pain. The body tolerance level to pain descreases when you are tired. Also your appetite is affected by sleep derivation. Study has shown that increased appetitie is a common symptom of sleep derivation.

Does my body shutdown completely when I sleep?

First your heart is definitely working during your sleep to circulate blood to all part of the body. Second, your brain functions throughout the process. It is as active as you are awake. Study has shown there are 5 distinctive brain waves that define sleep into 5 different stages.

What are the 5 stages of sleep?

Stage1 is the initial stage of sleep. The muscles are relaxed and you find yourself in a peaceful, pleasure and relaxing state. You are less aware of the external environment and you feel like floating or falling. In this stage, the eyes movement, heart rate and brain waves slow down and you can easily be woken up.

Stage2 is similar to stage1 except that the eyes movement stop, the brain waves are slower with occasional burst of rapid brain waves. You require a heavier touch, louder noise to awake you. Stage1 and stage2 last about thirty minutes.

This is the begining of deep sleep. In stage3, the brain waves slow down more but there is still occasional rapid waves. You are deeper into your sleep and have no awareness of the external environment. Hence it is more difficult to awake you as compare to stage1 and stage2.

In stage 4, you are in deep sleep. The brain wave is even more slower. This is truly a restful experience because the body muscles are now even more relaxed than when are awake. Your body has very little movement as your brain is not sending messages to the body muscles. However you still can be awakened but only with a much stronger stimulus.

This is the stage when your brain wave becomes very similar to that produced when your brain is in awake state. At this time, your eyes dart about in rapid movement and you start to dream. Your heart rate and blood pressure rise and fall along with what you experienced in your dream. However, your brain signal is blocked from reaching your body muscle. Thus you are not able to act out the dream that your brain is experiencing.

If muscles are paralysed during sleep, why do I wake up with erection at time?

Blood flow to genital organs is increased during sleep for both men and women. Men get erection and women become engorged mostly when their REM sleep begin (ie. the stage when dream started) and last for the whole of REM sleep. The content of dream, regardless of any sexual thoughts, has no effect on such response.

The cause of such behavior is not known but is believed that due to the paralysing of muscle, the intrinsic nervous tissue of these organs is allowed to act in an unoppoesed fashion which is freed from the inhibitions of the brain.

How many REM sleep will i go through in my sleep?

A sleep cycle consists of stage1 to REM. Normally this cycle is about 90 to 100 minutes long. An adult has 3 to 5 such sleep cycles per night of sleep.

Why do I yawn?

yawn Yawn is a phyiscal gesture that reflects the mental state of decreased in interest. Just like smiling or crying, yawning is a phyical action that shows your mental or emotional state. The intake of more air through your mouth has nothing to do with the body phyislogic function.

Why do i feel sleepier after sex?

The reason is you feel a sense of peacefulness and calmness after sexual orgasm. Intercourse does not trigger sleep. Instead, orgasm increases sleepiness in you. After sexual orgasm, your body muscle is relaxed and your mind is in a state of peacfulness. You are more lazy to move around and your brain waves is slower, inviting sleep to occur.

I don't experience orgasm while having body massage therapy. Why do I feel sleepier after the session?

The reason is the same as above. Such therapy makes you relax and feel a sense of calmness. When you are in such state, you allow sleep to occur.

Why does my husband fall asleep faster than i do after sex?

Majority of the people, male or female, feel sleepier after sexual orgasm. However men have a higher tendency of falling asleep. This is because of a chemical called Norepinephrine that produces inside them. During intercourse, such chemical is present in high level and drop soon afterward. Men feel sleepier when the level of Norepinephrine drops.

Grandma sleeps less than i do. Is there something wrong?

Sleep duration tends to fall with age. However, it is also true that people with Alzgeimer's disease have higher than age-appropriate fragmentation sleep.

I have heard that too much sleep is bad. Is this true?

Across studies, older adults who report sleeping eight hours have higher mortality. People who spend more than eight hours a night in bed regularly have been found to be less healthy (and have chronic illnesses), of lower socioeconomic status, and tend to be depressed. The long time in bed may be the result of rather than the cause of chronic ill health.