Irregular Sleep Patterns May Increase Risk for Dementia

• A new study shows that people who have irregular sleep patterns may have a greater chance of developing dementia than those who have more regular sleep patterns.
• When sleep becomes irregular, the circadian rhythm is negatively affected, which can result in issues with cognitive functioning.
• Experts say maintaining a consistent sleep schedule can help you sleep better.

Along with getting enough sleep, sticking to a consistent sleep schedule is essential to your overall health.

Now, a new study published in Neurology finds people who have very irregular sleep patterns may be at an increased risk of dementia compared to those who have more regular sleep patterns.

What to know about sleep and dementia risk

For approximately 7 years, researchers observed 88,094 people who were an average of 62 years old. Participants wore a wrist device for one week to analyze their sleep cycle and regularity of sleep.

Based on this data, the team developed a score for sleep irregularity.

Next, researchers examined the participants’ medical information to see who developed dementia.

They found that people who had the most irregular sleep were 53% more likely to develop dementia than people with moderate sleep irregularity.

“The association between irregular sleep and the risk of dementia was compelling, especially given that it was observed in such a large sample,” Matthew Pase, PhD of Monash University in Melbourne, Australia. “The findings were also independent of sleep duration and disruption, suggesting that sleep regularity is important in itself. This data suggests that when thinking about what constitutes good sleep, we (researchers and the public) should consider sleep regularity as well as overall sleep duration and quality.”

Pase, a co-author of the study, said that in future studies, they can investigate if sleeping regularly improves memory.

“Studies could also investigate the mechanisms linking sleep regularity to dementia. For example, are there links between sleep regularity and Alzheimer’s disease in the brain?” Pase said.

How to avoid irregular sleep

The human body has natural sleep-wake cycles or circadian rhythms that coincide with the time of day, according to sleep experts.

The circadian system refers to a pattern of day-night oscillation of neural, hormonal, and other regulatory system patterns that respond best to environmental light. This is particularly true of sunlight.

Experts say that having an irregular sleep pattern affects this system and may be a risk factor for cognitive decline.

“Irregular sleep patterns are a challenge to the circadian timing system, which operates in parallel to our sleeping and waking,” said Mary A Carskadon, PhD, Professor of Psychiatry and Human Behavior at the Warren Alpert Medical School of Brown University. “Sleeping provides a profound ‘darkness’ signal to the circadian system and this signal helps to set and stabilize circadian timing.”

Carskadon did not work on the study.

“Sleep as a human phenomenon, is meant to be synchronized with day-night rhythms,” said Dr. Sudha Tallavajhula, sleep neurologist with UTHealth Houston and medical director of the Neurological Sleep Medicine Center at TIRR Memorial Hermann. “Starting from specialized cells in our eyes, multiple networks work in tandem to orchestrate hormonal activity, immune function, and other critical organ system functions, all targeting the human rest-activity cycle.”

Tallavajhula did not work on the study.

Recent studies have found that cerebrospinal fluid can help remove “waste” from the brain during sleep.

“One newly discovered function of sleeping involves the brain’s glymphatic system, which is involved in clearing waste products from the brain,” Carskadon. “It’s not hard to see how a cascade of these processes might result in vulnerable accumulation of material that can compromise cognitive function, particularly over time.”

How to get better sleep

In terms of sleep regularity, going to sleep and waking up as close as possible to a routine schedule is important.

The U.S. Centers for Disease Control and Prevention recommends the following tips for getting better sleep:

• Go to bed at the same time every night and get up at the same time every morning.
• Keep your bedroom dark, comfortable, and relaxing.
• Avoid keeping electronics like your phone, tablet, or laptop in your bedroom.
• Avoid large meals, caffeine, and alcohol shortly before sleep.
• Get regular exercise.

Tallavajhula agrees a regular sleep schedule is key.

“The most common step that sleep medicine experts advise to improve sleep is institution of a regular schedule,” said Tallavajhula. “This trains the mind, similar to training the body in a gym.”

For some people, especially shift workers, it may not be possible to maintain a regular sleep time and wake-up time.

In that case, avoiding rotating shifts and sticking to an alternative sleep schedule may be beneficial, Tallavajhula advised.