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. [BACK]

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. [BACK]

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

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.

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. [BACK]

Insomnia refers to difficulty falling or staying asleep, or a perception of unrefreshing sleep.

Common Causes:

• Depression
• Excessive caffeine consumption
• Irregular sleep habits

Patients with persistent insomnia should be evaluated by a physician to rule out underlying depression, which often presents with early morning waking. Patients who are unable to sleep without sleeping pills may need to be referred to a Sleep Disorders Clinic. Most patients with insomnia can be managed with lifestyle modifications and medication, and do not usually need a sleep study. [BACK]

Abnormal behaviour in sleep often does not require specific treatment unless there is risk of injury, or if the abnormal movements disrupt sleep. Examples of abnormal movements disturbing sleep are restless legs syndrome and periodic limb movement disorder, in which excessive leg jerking before or during sleep causes insomnia or excessive daytime sleepiness.

The parasomnias are abnormal behaviours during sleep which can occur in children or adults:

1. Sleep terrors
2. Nightmares
3. Sleep talking
4. Teeth grinding
5. Sleep walking
6. Acting out dreams

A sleep study is frequently required to evaluate these conditions, which must be distinguished from seizures occurring during sleep, which can appear very similar. [BACK]

Some sleep disorders have a genetic component and may run in families, such as restless legs syndrome, obstructive sleep apnoea, narcolepsy and the parasomnias.

People who have irregular sleep schedules, including shift workers and those who travel across multiple time zones frequently are also at increased risk of developing sleep related problems.

Lifestyle factors such as excessive caffeine consumption, lack of regular exercise, poor stress management and smoking all contribute to sleep disturbances.

In general, the quality of sleep declines with age. As a result of this, as well as degenerative changes and weight gain which increase with age, sleep related disorders tend to become more frequent as we grow older. [BACK]

Most sleep disorders can be diagnosed with a good sleep history, including questions about the patient’s sleep habits, lifestyle, medications and a physical examination. A sleep study may be required in some patients. [BACK]

Sleep patterns can be studied in the laboratory using machines which record brainwave activity, breathing, heart rate and limb movements during sleep. The most common types of sleep studies are:

• Overnight polysomnography (PSG)
• Daytime nap test (also known as the multiple sleep latency test or MSLT).

PSG involves staying overnight in the sleep laboratory and being hooked up to a machine which is monitored by sleep technologists. At least 6 hours of sleep are recorded using electrodes attached to the scalp and limbs, special belts across the chest and abdomen, airflow monitors and ECG leads. PSG is usually indicated in patients in whom sleep related breathing disorders and abnormal movements in sleep are suspected.

The MSLT follows the overnight PSG, comprising four 20-minute naps at 2 hour intervals throughout the day. It is indicated for the diagnosis of narcolepsy and also to assess the severity of sleepiness in patients who complain of excessive daytime sleepiness. [BACK]

Most sleep disorders can be managed conservatively with a combination of good sleep education, medication and behavioural modification. In certain conditions like obstructive sleep apnoea, specific therapy may include positive airway pressure therapy (pressurised air delivered via a mask) or upper airway surgery.

Difficult cases are referred to physicians trained in the management of sleep disorders. Many Sleep Disorders Clinics are staffed by health professionals in multiple disciplines, such as neurologists, respiratory physicians, ENT surgeons, psychologists and psychiatrists. [BACK]

• Alexandra Hospital
  378 Alexandra Road
  Singapore 159964
  Tel: 6472 2000

• Changi General Hospital
  2 Simei Street 3
  Singapore 529889
  Tel: 6788 8833

• Gleneagles Hospital
  6A Napier Road
  Singapore 258500
  Tel : 6473 7222

• Institute of Mental Health
  10 Buangkok View
  Singapore 539747
  Tel: 6389 2200

• KK Women’s and Children’s Hospital
  100 Bukit Timah Road
  Singapore 229899
  Tel: 6293 4044

• Mount Elizabeth Hospital
  3 Mount Elizabeth, #02-00
  Singapore 228510
  Tel: 6737 2666

• National Neuroscience Institute
  11 Jalan Tan Tock Seng
  Singapore 308433
  Tel: 6357 7095

• National University Hospital
  5 Lower Kent Ridge Road
  Singapore 119074
  Tel: 6779 5555

• Sleep Disorders Unit
  Singapore General Hospital
  Outram Road
  Singapore 169608
  Tel: 6321 4402/ 6326 6202

• Tan Tock Seng Hospital
  11 Jalan Tan Tock Seng
  Singapore 308433
  Tel: 6357 7861

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