TAKE anyone with a psychiatric disorder and the chances are they don't sleep well. The result of their illness, you might think. Now this long-standing assumption is being turned on its head, with the radical suggestion that poor sleep might actually cause some psychiatric illnesses or lead people to behave in ways that doctors mistake for mental problems. The good news is that sleep treatments could help or even cure some of these patients. Shockingly, it also means that many people, including children, could be taking psychoactive drugs that cannot help them and might even be harmful.
No one knows how many people might fall into this category. "That is very frightening," says psychologist Matt Walker from the University of California, Berkeley. "Wouldn't you think that it would be important for us as a society to understand whether 3 per cent, 5 per cent or 50 per cent of people diagnosed with psychiatric problems are simply suffering from sleep abnormalities?"
First, we'd need to know how and to what extent sleep disorders could be responsible for psychiatric problems. In the few years since sleep researchers identified the problem, they have made big strides in doing just that.
Doctors studying psychiatric disorders noticed long ago that erratic sleep was somehow connected. Adults with depression, for instance, are five times as likely as the average person to have difficulty breathing when asleep, while between a quarter and a half of children with attention-deficit hyperactivity disorder (ADHD) suffer from sleep complaints, compared with just 7 per cent of other children.
Until recently, however, the assumption that poor sleep was a symptom rather than a cause of mental illness was so strong that nobody questioned it. "It was just so easy to say about a patient, well, he's depressed or schizophrenic, of course he's not sleeping well - and never to ask whether there could be a causal relationship the other way," says Robert Stickgold, a sleep researcher at Harvard University. Even when studies did seem to point in the other direction, the findings were largely overlooked, he says.