Sleepless nights can trigger euphoria, risky behaviour

Researchers at the University of California and Harvard Medical School studied the brains of healthy young adults and found that their pleasure circuitry got a big boost after a missed night's sleep.

But that same nerve cell pathway that stimulates feelings of euphoria, reward and motivation after a sleepless night may also lead to risky behaviour, their study suggests, according to a California university statement.

"We need to ensure that people making high-stakes decisions, from medical professionals to airline pilots to new parents, get enough sleep," said Matthew Walker, associate professor of psychology at California who led the study.

"Based on this evidence, I'd be concerned by an emergency room doctor who's been up for 20 hours straight making rational decisions about my health," the Journal of Neuroscience quoted Walker as saying.

The body alternates between two main phases of sleep during the night -- Rapid Eye Movement (REM), when body and brain activity promote dreams, and Non-Rapid Eye Movement (NREM), when the muscles and brain rest.  Previous brain studies indicate that these sleep patterns are disrupted in people with mood disorders.