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Sunday, 23 December, 2001, 00:25 GMT
Scientists 'unlocking body clock'
Sleep research, BBC
Scientists are probing sleep disorders
A team of researchers believes it has found another component in the complex system that makes us sleep at night - and wake in the morning.

They are hopeful that their finding may one day contribute to improved treatments for people with sleep disorders.

Humans run their lives by circadian rhythms, and have an automatic system which responds to day and night to allow sleep and wake in turn.

If you could figure out the factors that are promoting wakefulness and sleep, that could in principle be turned into much better drugs for particular sleep disorders

Professor Chuck Weitz, Harvard Medical School
However, the method by which the body sets and adjusts the rhythm is still relatively little understood.

The researchers, from Harvard Medical School in Boston, US, say they have found a link in the chemical chain by which the body sends orders to regulate the cycle.

The chemical they have found in experiments using hamsters and mice is a growth factor called TGF-alpha. It appears to be present in both the part of the brain known to be linked to the sleep-wake cycle, and the hypothalamus, the gland which secretes the hormones key to controlling the body's slumbers.

Professor Chuck Weitz, the lead researcher, said: "If you could figure out the factors that are promoting wakefulness and sleep, that could in principle be turned into much better drugs for particular sleep disorders."

Signalling link

The research also suggests that receptors on the hypothalamus which are primed to receive TGF-alpha may not simply be getting information from the brain, but also from the retinas of the eyes.

This is because there are also signs that TGF-alpha is produced there as well.

This could mean that the amount and timing of the light coming through the eyes is able to effect an adjustment to the body clock, allowing someone to change their sleeping and waking habits in tune with the changing seasons.

Some doubts

However, not all experts are convinced that TGF-alpha necessarily represents the key to understanding the mechanism lying behind the body clock.

Dr Michael Hastings, from Cambridge University, UK, said that this growth factor was not a valid target for future treatments because it performed other tasks elsewhere in the body, and interfering with it in relation to the body clock could have a damaging effect elsewhere.

He said: "This is found all over the place, and there are many other growth factors involved in this signalling process."

The research paper was published in the journal Science.

See also:

11 Sep 01 | Health
Night shift link to heart problem
21 May 01 | Health
Jetlag 'shrinks the brain'
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