Do you find it difficult to wake up on Monday mornings? Do you ever have difficulty paying attention or concentrating at work? Do you ever fall asleep while driving? If so, you are familiar with the powerful need for sleep.

However, most people experience difficulty in sleeping at some time or other. Some suffer from chronic, long-term sleep disorders while some experience occasional sleeping problems. These disorders and the resulting sleep deprivation interfere with their work, driving, and social activities.

Professor Damon T. K. Choy from Ruijin AmMed Cancer Center explained that sleep has two phases: rapid eye movement and non-REM. REM sleep, also known as "dream sleep," is the phase of sleep in which the brain is active.

NREM is the quiet or restful phase of sleep. The stages of sleep occur in a repeated pattern of NREM followed by REM.

Each sleep cycle lasts about 90 minutes and is repeated four to six times during a seven-to-eight-hour sleep period. The four major categories of sleep disorders that interfere with normal sleep patterns include: the inability to fall asleep and stay asleep (insomnia); disorders of the sleep-wake cycle; disorders associated with sleep stages, or partial waking (parasomnia); and excessive sleepiness.

According to him, many overweight people suffer from sleep apnea and have difficulty staying awake during the daytime. Obesity is not the only cause. Other causes include a narrowed airway, high blood pressure, smoking, age, or having a family history of sleep disorders.

Sleeping problems are also associated with strokes, cancers, head injuries and Alzheimer's disease. These sleeping problems may arise from changes in the brain regions and neurotransmitters that control sleep, or from drugs and treatments used to control symptoms of other disorders.

However, for most of us, sleep disorders occur occasionally as a result of tension, stress and anxiety - and of course the more anxious we get about our insomnia, the worse it gets. It is often caused by fear, stress, anxiety, medications, herbs, caffeine, depression, or sometimes for no apparent reason at all.

Getting too little sleep creates a "sleep debt," like being overdrawn at a bank. Eventually, your body will demand that the debt be repaid.

Many studies make it clear that sleep disorders and sleep deprivation is dangerous. Most people are aware of obvious short-term effects of sleep deprivation including exhaustion, fatigue, and a general lack of energy, but they're less aware of some of the more serious physical consequences due to frequent insomnia. For example, people who have long-term sleep deprivation are twice as likely to die of heart disease.

(Shanghai Daily June 3, 2008)