It often seems the older a person gets, the less they sleep, but new research suggests that inconsistent sleep patterns might predict a future diagnosis of Parkinson’s disease.

Researchers who studied 2,930 older men for more than a decade found that those with a particular sleep problem — called circadian rhythm disruptions — were three times more likely to develop Parkinson’s disease. A central nervous system disorder, Parkinson’s affects balance and movement and often causes tremors.

Circadian rhythms tell the body when to wake up and when to go to sleep. They rely, in part, on light. When it’s light, the body is supposed to be awake, and when it gets dark, it’s time to sleep. The normal functioning of this system can be disrupted by lifestyle choices, such as working nights or using a cellphone at bedtime.

Also, sometimes with age, this internal “clock” becomes inconsistent. Older adults often sleep less, and their sleep patterns might change as they become tired in the early evening and wake up early in the morning.

“When we talk about circadian problems … it involves the activity level a person has during the day and during the night, and how regular that pattern is,” Leng said.

In 2003, when the study began, participants were asked to wear a device called an actigraph for three days. It detects slight movements in the wrist and makes it possible to figure out when a wearer is resting and when they are active. This cycle of rest and activity is key to understanding if a person’s circadian rhythms are normal.

Participants were generally healthy when the study began, and none had Parkinson’s disease. Over the next 11 years, however, 78 men were diagnosed with the disease. Those whose actigraph readings revealed abnormal circadian rhythms had triple the odds for Parkinson’s, the study found.

That remained true even after researchers accounted for other sleep problems, including apnea, involuntary leg movements, and sleep inefficiency (time spent asleep after shutting off the lights).

The findings were published online June 15 in JAMA Neurology.

People can take steps to normalize their body clock through light therapy — exposure to bright lights during daytime hours — and by taking melatonin. If circadian disruptions are found to be a cause of Parkinson’s rather than a symptom, these treatments could potentially be used to help prevent it.

Beck suspects that circadian disruptions are most likely an early symptom of Parkinson’s rather than a cause. Still, he said that this research is an important piece of the puzzle that is Parkinson’s — a disease for which there are treatments to alleviate symptoms but no known cure or preventative drug.

Sleep-related problems are among the most common complaints made by Parkinson’s patients, and Beck hopes that this study will increase the urgency of studying the role that circadian rhythms play.

Parkinson’s is the second most common neurodegenerative disorder, after Alzheimer’s disease. More than 500,000 people in the United States have been diagnosed with Parkinson’s, most after age 60.

More information

There’s more about Parkinson’s disease at the Parkinson’s Foundation.

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