How do I know how much sleep I require?

I have been having sleeping problems lately. I wake up at 5am every morning and I can't get back to sleep again. How many hours of sleep should I be getting?

Everyone needs different amounts of sleep. The amount of sleep you need depends on your age, your individuality and even your pregnancy status.

For example, most adults need around seven to eight hours a night. But some people need only five to six hours a night, and others need even more, like nine hours a night.

Babies usually require 16 hours of sleep a day. As they grow older, they sleep less.

Teenagers usually need nine hours of sleep a night.

Women who are in the first three months of their pregnancy usually need more sleep than what they normally require.

Research has shown that adults who get fewer than seven hours of sleep at night have more difficulty concentrating and have more mood swings than people who sleep more than seven hours.

How would I know how much sleep I require?

If you feel refreshed the next morning after a certain amount of sleep, then that is the amount of sleep you need.

But if you feel drowsy during your activities throughout the day, it means you haven't had enough sleep.

The amount of sleep you need also increases if you have been deprived of sleep in the previous days. This is called "sleep debt". Your body needs that debt to be repaid.

Unfortunately, most of us don't repay that debt, so the sleep debt accumulates. And as time goes on, our judgement, concentration, memory, focus, and everything else becomes impaired.

Too little sleep may also weaken your immune system and increase your chances of getting illnesses like the common cold and flu.

If you take alcohol when you are having sleep deprivation, this enhances the effects of alcohol on your body, and you become even more drowsy.

What happens when I sleep?

Our sleep can be divided into two types: REM (Rapid Eye Movement) sleep and non-REM sleep.

Non-REM sleep has four stages of increasingly deep sleep from Stage 1 (lightest) to Stage 4 (deepest).

If your sleep through any of these stages is interrupted, you won't be able to transit from one stage of sleep to another easily. So, you will go into sleep debt and feel tired and fatigued the next day.

If I wake up early and cannot go back to sleep, does that constitute insomnia?

Yes. Insomnia covers the gamut of problems like trouble getting to sleep, trouble sleeping throughout the night, waking up frequently at night, and waking up too early.

Sometimes, you can't remember if you woke up during the night, but this can be manifested in tiredness, sleepiness and fatigue throughout the day.

Insomnia can be caused by stress, anxiety, depression, poor sleep habits, taking certain types of medicine, taking too much alcohol or caffeine, and jet lag.

Other than insomnia, are there any other types of sleep disorders?

Yes. There are many.

Sleep apnoea is a type of sleep disorder where your upper airways become obstructed, either partially or completely for short periods of time, waking you up.

It can cause severe daytime drowsiness and impaired concentration, and more serious problems like high blood pressure, stroke and heart attack.

There are also pregnancy associated sleep disorders.

Pregnant women in their first three months often get woken up at night because of frequent urination, and wake up early because of morning sickness.

In the second and third trimesters of pregnancy, you may experience vivid dreams and physical discomfort from your womb pressing down on other organs.

There's a disorder called narcolepsy, where some patients suddenly get dramatic and uncontrolled "sleep attacks" where they suddenly fall asleep in the middle of what they are doing.

But in reality, this is rare. Most narcolepsy patients do not have "sleep attacks", but experience constant sleepiness throughout the day.

For people who have Restless Legs Syndrome, they feel an urge to move their legs during the evening and night to get some relief.

Many have excessive, rhythmic or cyclic leg movements during sleep, which naturally cause a poor night's sleep.

Why do some people have nightmares?

Nightmares are frightening dreams that happen during the REM stage of your sleep.

They can be caused by stress, anxiety and certain types of drugs, like some beta-blockers used in treating high blood pressure. But there is often no clear cause.