January 29, 2009

A hormone may regulate sleep

Falling asleep involuntarily during the day poses a very real and dangerous problem, Canadian researchers said.

Researchers at the Montreal Neurological Institute at McGill University demonstrates sleep-wake states are regulated by two types of nerve cells, melanin-concentrating hormone neurons and orexin neurons, which occupy the same region of the brain, but perform opposite functions.

The study is the first to discover that melanin-concentrating hormone neurons are activated during sleep and could thus be important in regulating the sleep state.

The study, published in the journal Proceedings of the National Academy of Sciences, provides deeper understanding of the sleep-wake cycle and vital insight into the basis of sleep disorders such as narcolepsy and possibly also other diseases such as depression and Parkinson's.

Remarkably, what we found is that melanin-concentrating hormone neurons are actually silent during waking, which is a surprising finding especially in this wake-promoting region of the brain. The neurons fire during sleep, and are most active during rapid eye movement sleep, principal investigator Dr. Barbara Jones said in a statement.