Poor sleep can accompany schizophrenia.

The body's internal biological clock coordinates a host of rhythms--from hormone production to sleep-wake times--on about a 24-hour cycle. Although everyone's clock tends to run a little fast or slow, sunlight usually resets it. In people with schizophrenia, however, this clock can be seriously broken, a preliminary study finds.

Russell Foster of the University of Oxford in England and his colleagues strapped wristwatch-style activity monitors onto 14 volunteers with schizophrenia. They didn't hold jobs or otherwise have to wake up at a specific time each day. The team also monitored an equal number of healthy unemployed people. The neuroscientists recorded each subject's activity and rest cycles for up to 3 years.

Healthy people maintained standard, relatively unvarying daily patterns. The surprise was how erratic sleep patterns were in all the recruits with schizophrenia, Foster says. The scientists also documented alterations in the timing of hormone production in the participants with schizophrenia, which confirmed that their body clocks were disturbed.

Internal clocks in a few of those people had "lost rhythmicity altogether," Foster notes, and drifted regardless of the daynight cycle. Other participants had fairly consistent sleep-wake cycles, but they tended to be "horribly delayed"--almost as if they were seriously jet lagged, he reported last month at the Euroscience Open Forum in Munich.

These people aren't necessarily sleep deprived. "It's the timing of their sleep that's so very different," Foster says. Indeed, he told Science News, "trying to engage socially at a time their body clock is telling them to sleep may exacerbate their [psychosis]." That's why, he argues, efforts to repair clock rhythm through light or sleep therapy might reduce the severity of some schizophrenia symptoms.