Researchers have suggested that disabling a gene that helps keep track of time makes brain cells more likely to die spontaneously, and they believe that this connection may help strong connections between sleep problems and neurodegenerative conditions such as Alzheimer's disease.

Scientists at Washington University School of Medicine in St. Louis and the University of Pennsylvania have shown that brain cell damage similar to that seen in Alzheimer's disease and other disorders results when a gene that controls the sleep-wake cycle and other bodily rhythms is disabled.

The researchers found evidence that disabling a circadian clock gene that controls the daily rhythms of many bodily processes blocks a part of the brain's housekeeping cycle that neutralizes dangerous chemicals known as free radicals.

"Normally in the hours leading up to midday, the brain increases its production of certain antioxidant enzymes, which help clean up free radicals," first author Erik Musiek, assistant professor of neurology at the School of Medicine, said. "When clock genes are disabled, though, this surge no longer occurs, and the free radicals may linger in the brain and cause more damage."

Musiek studied mice lacking a master clock gene called Bmal1. Without this gene, activities that normally occur at particular times of day are disrupted.

Musiek found that as the mice aged, many of their brain cells became damaged and did not function normally. The patterns of damage were similar to those seen in Alzheimer's disease and other neurodegenerative disorders.

The study was published in The Journal of Clinical Investigation.