Sleep Disorders
  1. What is Normal Sleep?

    Normal sleep consists of cycles of non-rapid eye movement (NREM) sleep alternating with rapid eye movement (REM) sleep. NREM sleep consists of light sleep and deep sleep. REM sleep is also known as dream sleep. The function of sleep is believed to be restorative, a time of rest and repair for the body.

    Adults need an average of 8 hours of sleep (range 6 - 10 hours). It is normal to fall asleep within 10 to 20 minutes of going to bed, to wake up spontaneously once or twice in the night then fall back to sleep readily, and wake up feeling refreshed. Children need more sleep and tend to have more deep sleep, while the elderly have more frequent awakenings and less deep sleep.
  2. What happens when we do not get enough sleep?

    The serious short and long term consequences of sleep deprivation reflect the important restorative functions of sleep. When we do not get enough sleep, our memory, concentration, alertness and mood are affected. Daytime sleepiness leads to poor school or work performance and can result in serious accidents. Left untreated, long term sleep disturbances decrease quality of life, and can lead to increased morbidity and mortality.
  3. What are Sleep Disorders?

    Sleep disorders are sleep-related disturbances due to underlying medical problems, lifestyle and environmental factors which usually cause sleep disruption, leading to insufficient or poor quality sleep.

    The most common symptoms of sleep disorders are:
      excessive daytime sleepiness insomnia breathing disturbances abnormal behaviour during sleep
  4. What causes excessive daytime sleepiness?

    Common causes:
    • Insufficient sleep: many people do not get sufficient sleep because of lifestyle choices.
    • Obstructive sleep apnoea, which refers to cessation of breathing during sleep: patients may be obese or have blockage of their breathing passages due to problems in their nose or throat.
  5. Uncommon but important cause:
    • Narcolepsy: a sleep disorder which is associated with sudden loss of muscle tone, hallucinations and muscle paralysis on waking.
    • People with excessive daytime sleepiness severe enough to cause social or occupational disruption should undergo formal evaluation by a physician. Those with suspected sleep apnoea or narcolepsy usually need to undergo sleep studies.