BY JESSICA JAGANATHAN

DOCTORS say it is important to find out the underlying cause of insomnia so that it can be treated properly and the appropriate medication be dispensed.

Dr Lim Li Ling, medical director and consultant neurologist at the Singapore Neurology and Sleep Centre in Gleneagles Medical Centre, said there are three most common reasons for insomnia: Stress, anxiety and depression.

She added that for anxiety and depression, anti-depressants were more useful to improve the patients' mood, instead of sleeping pills which could depress them further as the pills do not correct the biochemical imbalance. 'So, that diagnosis must never be missed,' she said.

Dr Lim suggested that doctors get their patients to fill out a questionnaire about symptoms, to rule out depression or anxiety.

For stress-related insomnia, if doctors catch the patients within the first four weeks, correct information on good sleep hygiene will help, she said. 'With limited intermittent use of sleeping pills for the short term, they can usually get out of it.'

There are various types of sleeping pills. Benzodiazepines, which are an older class, are the most commonly prescribed.

• Short-acting benzodiazepines: These are generally used for patients who have difficulty falling asleep but without any daytime anxiety, said principal clinical pharmacist Ng Boon Tat from the Institute of Mental Health. These include brand names such as Ativan, Dormicum and Lexotan.
  
  
• Long-acting benzodiazepines: These are used to treat insomnia in patients with daytime anxiety and cause drowsiness the next day. They include diazepam, or more commonly known as Valium.
  
  
• Z drugs: Newer class of sleeping pills which are more expensive and have similiar effects to short-acting benzodiazepines, without the depressant effect. These include Stilnox and Innovane.
  
  
• Sedative antihistamine: They are used as treatment for allergies and running nose, said Mr Ng. Side effects include dry mouth and constipation. Although they cause drowsiness, its purpose as a sleeping pill has not been widely studied, he said. Common ones are Atarax and Paxadorm.

For more details, patients can refer to a book being launched by The Singapore Sleep Society called Sleep Medicine: The Clinical Guide To Common Sleep Disorders. It will be available at certain bookstores.

This article was first published in The Straits Times on Jan 2, 2009.