New discovery may lead to new drugs to regulate sleep

Aug 19 2008

A team of scientists from Oxford University in the UK have discovered the reason why people feel drowsier in dim lighting and more alert in bright white light.

They have found previously unknown cells in the eye known as the retinal ganglion cells, that respond to blue light which shifts the body clock to new time zones.

A team led by Professor Russell Foster have found that these light sensors do more than regulate our body clocks as they also play an important role in directly regulating levels of sleepiness and alertness.

Professor Foster says the cells are a brand new target for the development of highly selective drugs to regulate sleep and wakefulness and by targeting the specific mechanism controlling the action of retinal ganglion cells, it may be possible in the future to develop much more sophisticated treatments.

Professor Foster believes the results may also have enormous practical value as drugs currently available for the regulation of sleep and alertness, are he says ,relatively 'crude' and he suggests a new class of sleeping pill and stimulants that would have the same effect as bright light, or darkness, depending on the design of the drug, could be in the pipeline.

Professor Foster already has some possible chemicals in mind but he believes it will take another decade of tests on patients to determine if the drugs will be of value for either treating insomnia or excessive sleepiness.

He says the aim is to find drugs that act on the same pathway from the eye to the brain used by the cells that respond to blue light which could result in a much more effective drug, free of side effects.

Professor Foster says while it was known that dim light made people sleepy and bright light made them more alert, why that was so was unclear.

It seems that these specialised cells in the retina detect light and send brightness information to those regions of the brain that regulate sleep and levels of arousal.

The team conducted their research with mice in which the cells had been genetically turned-off and they found that the effects of light on sleep and alertness was completely abolished even though the other retina cells responsible for vision were working normally in these mice.

Professor Foster says a previously unknown pathway in sleep regulation was revealed which was an unexpected result.

Professor Foster from the Nuffield Laboratory of Ophthalmology, has been a staunch campaigner on the value of sleep and how modern society is sleep deprived, jeopardising he says, mental dexterity, memory and health.

He believes sleep and the disruption of sleep patterns is a huge problem in the 21st century, which is the result of a 24/7 working culture of long hours and shift work, conspiring to demote sleep.

The researchers say finding a previously unknown pathway in sleep regulation and identify the signaling system offers a potentially new pharmacological target for the selective manipulation of sleep and arousal states.

The research is published in the journal Nature Neuroscience.