SCIENCE FOCUS

Studly links breathing disorders to insomnia

An experimental study has awakened doctors to another possible cause of chronic sleeplessness

PUBLISHED : Sunday, 30 December, 2012, 12:00am
UPDATED : Sunday, 30 December, 2012, 3:54am

Insomnia is a disorder in which the sufferer is unable to fall asleep, or stay asleep, as long as desired. Sometimes insomnia is a transient condition due to emotional stress, anxiety or a response to certain medications or medical conditions.

Insomnia without any known cause is termed as primary insomnia. Chronic insomnia is diagnosed if the condition lasts for longer than a month.

Regardless of the nomenclature, insomnia has significant physiological and psychological consequences. Restorative sleep is as important to our well-being as healthy food and regular exercise.

Insomnia sufferers report a diminished quality of life. If unresolved, chronic insomnia causes slowed reactions, mental health issues such as depression or anxiety, physical ailments such as obesity and increased risk for cardiovascular diseases as well as lower performance at work or at school.

In highly stressed Hong Kong, insomnia is common. Indeed, according to a recent study by the department of applied social studies at the City University of Hong Kong, 68.6 per cent out of 529 Hong Kong college students surveyed admitted to being insomniacs with reported psychosocial factors.

Another Chinese University of Hong Kong study by Zhang J et al, published in Sleep Medicine, which tracked more than 2,000 Chinese adults over five years, confirmed that chronic insomnia is a persistent problem in the city.

It is worth noting that insomnia is a symptom, not a disease. The main therapeutic approaches to chronic insomnia are cognitive behavioural therapy (CBT), or "talk therapy", and sleep medicines.

CBT is designed to identify the underlying causes of insomnia and seek to empower patients with the knowledge of sleep patterns and ways to improve sleep habits. CBT is individually tailored, ranging from correcting misconceptions on sleep to practising sleep hygiene - avoid turning on the television at bedtime or exercising strenuously just before sleep - to relieving stress and anxiety.

For what it's worth, CBT works better than sleep medicines, as the latter do not correct the underlying cause.

A recent experiment published in the journal Sleep is challenging the conventional dogma. The study authors enrolled 20 adult patients with chronic insomnia who also reported impaired quality of life.

All the patients underwent a formal sleep study in a laboratory where they each spent a night wired to sensors that tracked brain waves and breathing patterns.

The results were then classified into "subjective", which were self-reported reasons for insomnia, and "objective", which is the data gleaned from the sleep studies.

In the subjective portion, the participants reported a myriad of causes for their insomnia, including nightmares, the need to urinate, racing thoughts, bedroom distractions and pain. But no one identified breathing symptoms as a cause.

In the objective portion, the researchers found 90 per cent of the awakenings were brought on by breathing events such as abnormally slow breathing (hypopnoea), cessation of breathing (apnoea) or respiratory effort-related events.

In fact, when the researchers charted every awakening, defined by when brain waves shifted to a waking state for at least 16 seconds, it was associated with a breathing issue causing oxygen intake to dip.

In other words, the patients' subjective sensation of sleep loss was, in fact, due to oxygen-carbon dioxide mismatch from abnormal breathing. These results suggest that a significant portion of so-called "sleep disorder/insomnia"may in fact be down to breathing disorders.

Although the sample size was small, the study is forcing scientists and doctors to re-examine the prevailing definition of insomnia.

Doctors who see patients complaining of chronic insomnia who have not responded to current treatments may well consider the patient's breathing pattern.

In sleepless Hong Kong, this paradigm change will not only have significant diagnostic ramifications but economic ones too.

Dr Ernie Yap practises internal medicine in the US

 

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