WASHINGTON: Ever wondered why we sleep? Well, a new study based on the roundworm C. elegans has provided the answer, by identifying a gene that regulates sleep.

The study, led by David M. Raizen, MD, PhD, Assistant Professor of Neurology, stated that the round worm has a sleep-like state.

In the study, the researchers showed that there is a period of behavioural serenity during the worm's development called lethargus that has sleep-like properties.

"Just as humans are less responsive during sleep, so is the worm during lethargus. And, just as humans fall asleep faster and sleep deeper following sleep deprivation, so does the worm," Nature quoted Raizen, as saying.

The research team used C. elegans as a model system to identify the gene that regulates sleep. This gene, which encodes a protein kinase and is regulated by a small molecule called cyclic GMP, has been previously studied but not suspected to play a role in sleep regulation.

By demonstrating that worms sleep, the researchers have not only showed the ubiquity of sleep in nature, but also propose a compelling hypothesis for the purpose for sleep.

Since the time of lethargus coincides with a time in the round worms' life cycle when synaptic changes occur in the nervous system, they propose that sleep is a state required for nervous system plasticity.

In other words, in order for the nervous system to grow and change, there must be down time of active behaviour.

The findings suggest a potential role for this gene in regulating human sleep and may provide an avenue for developing new drugs for sleep disorders.