Researchers have discovered the mechanism that causes the brain to switch from being awake to sleeping, according to a study from Washington State University.

The analysis is expected to help scientists focus on finding ways to develop new sleep aids and even treatments for strokes and brain injuries.

"We know that brain activity is linked to sleep, but we've never known how," said James Krueger, WSU neuroscientist and lead author of a paper in the latest edition of the Journal of Applied Physiology.

"This gives us a mechanism to link brain activity to sleep. This has not been done before."

In an interview with Postmedia News, Krueger said the way we sleep goes against what science believed previously.

"Our work also emphasizes that sleep begins as a local process driven by cell activity."

Krueger said the view is in contrast to the current sleep research that views sleep as being imposed upon the brain by sleep regulatory circuits.

"The problem with that view is that despite millions of cases of stroke (brain damage) or intentional lesions to those circuits, a sleepless human or animal has yet to be described (with exception of patients in a coma, which is neither a wake nor sleep state)," he said.

The researchers documented how ATP (adenosine triphosphate), the fundamental energy currency of cells, is released by active brain cells to start the molecular events leading to sleep. The ATP then binds to a receptor responsible for cell processing and the release of cytokines, small signalling proteins involved in sleep regulation.

By charting the link between ATP and the sleep regulatory substances, the researchers have found the way in which the brain keeps track of activity and ultimately switches from a waking to a sleeping state. The study shows that ATP is the signal behind those changes.

The mechanism of chemical transmitters and proteins opens the door to a more detailed understanding of the sleep process and possible targets for drugs and therapies aimed at the costly, debilitating and dangerous problems of fatigue and sleeplessness.

An estimated four to seven million Canadians suffer sleep disorders.

Sleep disorders affect between 50 and 70 million Americans, according to the Institute of Medicine of the National Academies in the U.S. The Institute also estimates the lost productivity and mishaps of fatigue cost U.S. businesses roughly $150 billion U.S., while motor vehicle accidents involving tired drivers cost at least $48 billion U.S. annually. No Canadian statistics were made available.

Almost everyone will on occasion, have a problem with sleep, sometimes lasting substantial periods of time, Krueger said.

The link between sleep, brain cell activity and ATP has many practical consequences, Krueger said.

- The study provides a new set of targets for potential medications.

- Sleep disorders, such as insomnia can be viewed as being caused by some parts of the brain being awake while other parts are asleep, giving rise to new therapies.

- ATP-related blood flow observed in brain-imaging studies can be linked to activity and sleep.

- Researchers can develop strategies by which specific brain cell circuits are oriented to specific tasks, slowing fatigue. It may also clear the way for stroke victims to put undamaged regions of their brains to better use.

- Brain cells cultured outside the body can be used to study brain cell network oscillations between sleep-like and wake-like states, speeding the progress of brain studies.