Dementia: Irregular sleep patterns linked to higher risk

  • Scientists report that people with irregular sleep patterns have a higher risk of dementia.
  • Sleep regularity is going to sleep and waking up at the same general time each day.
  • Sleep irregularity has also been associated with cardiovascular disease, metabolic disorders, depression, and atherosclerosis.

People with irregular sleep patterns might have a higher risk of dementia than those with regular sleep patterns, according to a new study published in the journal Neurology.

Sleep regularity is how consistent a person is at going to sleep and waking up at the same general time each day.

To measure this, 88,094 people wore a wrist device that measured their sleep cycle for seven days. Participants had an average age of 62.

Researchers used the data from the wrist device to calculate the regularity of sleep and the probability of a person being in the same sleep state (asleep or awake) at any two time-points, 24 hours apart. They averaged this data over seven days.

Participants were scored based on sleep regularity using a scale of 0 to 100. For example, those who went to sleep and woke up at the exact same time each day received a score of 100. Meanwhile, individuals who went to sleep and woke up at different times each day received a score of zero.

Those in the lowest 5% had an average score of 41. Those in the highest 5% had an average score of 71. The overall average was 60.

During an average follow-up period of seven years, 480 participants developed dementia.

The researchers reported that people with irregular sleep patterns were 53% more likely to develop dementia than those with midrange scores. Having the most regular sleep pattern did not decrease the dementia risk compared to the group in the middle.

Sleep irregularity and dementia risk

Although the scientists adjusted for several factors that can affect the risk of dementia, they said they could not rule out that another unknown factor may play a role in the association between sleep regularity and dementia.

“This study is intriguing and it has good research,” said Dr. Steven Feinsilver, the director of sleep medicine at Northwell Lenox Hill Hospital in New York who was not involved in the study. “But I am not sure that it proves anything. Does poor sleep cause dementia or does dementia cause poor sleep?”

“We sleep to clear our brains of toxins. It might also help other parts of the body, but the main reason we need sleep is to keep our brains healthy,” Feinsilver told Medical News Today. “The regularity of your wake time is more important than the regularity of the time you go to sleep.”

“If your sleep is regular, it is better for you, but the quality of your sleep also matters. Using sleeping pills can help, but it is probably not the same quality of sleep,” he added. “[Some medications] make you sleepy and might help you get to sleep, but they aren’t meant for sleep. People typically don’t feel as good the next day when they take antihistamines to get to sleep, but they often do if they take sleeping pills. There is still a lot we don’t understand about sleep.”

Changing your sleep patterns

The Centers for Disease Control and Prevention suggests that most adults sleep seven or more hours per night.

The National Institutes of Health provides suggestions for changing your sleep patterns:

  • Go to bed and wake up at the same time each day.
  • Use the hour before bed as quiet time.
  • Avoid large or heavy meals within a few hours of bedtime.
  • Avoid nicotine and caffeine at night.
  • Be more active during the day.
  • Find calming, relaxing activities to do before bedtime, such as reading or taking a bath.
  • Create a soothing, quiet, dark area to sleep.

“It is important to prioritize sleep health,” said Dr. Scott Kaiser, a geriatrician and the director of geriatric health for the Pacific Neuroscience Institute in Santa Monica, California, who was not involved in the study. “Sleep hygiene – preparing your environment, going to and getting up at the same time – is all very important.”

“This study raised good questions because we do know there is a connection between good sleep and brain health,” Kaiser told Medical News Today. “Sleep aids have potentially significant side effects and can increase the risk of confusion and falling. They also don’t always give restorative sleep. The best way to combat insomnia is with cognitive behavioral therapy. Changing sleep patterns takes a concentrated effort, especially in the age of electronics.”

“Sleep hygiene is so very important,” he added. “It is amazing how many of us have poor sleep hygiene. Although there are certainly other lifestyle factors that contribute to dementia, sleep is one we can focus on by being consistent.”

Other health problems connected to irregular sleep patterns

Over the past several years, scientists have associated irregular sleep patterns to various health issues:

  • A study published in Diabetes Care in 2019 reported that not having a regular bedtime/wake-up schedule can increase the risk of obesity, high cholesterol, hypertension, high blood sugar, and other metabolic disorders. The study indicated that each hour of variability could increase the risk by 27%.
  • In 2021, a study conducted at the University of Michigan’s academic medical center found that getting fewer hours of sleep or staying up late most nights is connected to bad moods and depression.
  • A 2023 study by the American Heart Association stated that adults 45 and older who fell asleep at different times each night and slept an inconsistent number of hours were more likely to develop atherosclerosis.
  • A 2023 study published in the journal Hypertension reported that people who varied the time they went to sleep and woke up were more likely to have high blood pressure.

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