Obstructive Sleep Apnoea:

A potentially dangerous problem in which breathing stops for several seconds, rousing the patient enough to start him breathing again.

This can happen 20 to 30 times an hour, disrupting rest and leaving the patient exhausted the next day.

Restless Leg Syndrome (RLS) & Periodic Limb Movement Disorder (PLMD):

The two often go together. RLS patients cannot lie still; they feel an irresistible urge to move their arms or legs while lying down.

Some feel a tingly or creepy sensation in their limbs, which is relieved by movement.

Those with PLMD involuntarily jerk their limbs while asleep. Frequent jerks disrupt their sleep, so they wake up unrefreshed.

Insomnia:

This is difficulty in getting to sleep coupled with waking up too early. It can be induced by stress.

It is fairly common in teenagers, whose body clocks are changing, causing them to want to go to bed late and rise later.

Sleep Walking:

This is more common in children and is often associated with bed-wetting.

The child remains in deep sleep while walking or doing other things.

In adults, it may be caused by lack of sleep or triggered by some medicines.

Narcolepsy:

A disorder which causes the person to fall asleep suddenly, usually when doing something monotonous. It can even occur in the middle of a meal or conversation.

This story was first published in The Straits Times on Jan 5, 2009.

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