Gene discovery sheds light on sleep requirement

US researchers have identified a single gene alteration that controls the amount of time a fruit fly sleeps for. The discovery could lead to new ways of treating sleep disturbances in people, say the scientists, who are based at the University of Wisconsin Medical School. The findings, published in the journal Nature, could also help explain why some people only need three or four hours sleep a night.

Fruit flies, like humans, sleep between 6-12 hours per night. However, after a round-the-clock study of 9,000 flies, the US team found a few that could function on just three or four hours sleep. The short-sleeping flies, named 'minisleepers', performed normally in a series of tests, although they did have a shorter lifespan than flies that slept for the usual length of time.

The minisleeper flies had a mutation in a gene called 'Shaker', which makes a protein that helps control the flow of potassium into cells - which in turn affects their electrical activity. Recent studies suggest that this process is also involved in promoting sleep in humans. The ability to sleep for less time without any loss of mental or physical performance appears to run in some families, suggesting it is influenced by genes.

Team leader Chiara Cirelli said that although the research was carried out in flies, it was relevant to people, saying 'this isn't some obscure fly gene'. In mammals, sleep is characterised by hallmark brain waves, which are slower during deep sleep. Cirelli explained that 'humans have the same kind of genes and potassium channels', adding 'our hypothesis is that if you don't have potassium channels, you won't get slow waves. The cell membrane will remain activated, preventing long periods of deep, non-REM sleep'. Understanding the proteins involved in sleep could help develop new drugs to help with sleep disorders such as narcolepsy and insomnia. However, the scientists stress that sleep is a 'highly complex activity', and probably involves many genes.