People with very irregular sleeping patterns may have a high risk of developing dementia, a new study has found.
The findings, published Wednesday in the journal Neurologyrevealed that the regularity of a person's sleep – that is, going to sleep and waking up at the same time every day – is an important factor behind a person's risk of dementia.
“Sleep health recommendations often focus on getting the recommended amount of sleep, which is seven to nine hours per night, but there is less emphasis on maintaining regular sleep schedules,” said study author Matthew Paul Pase, from Monash University, Australia.
Although previous studies have linked irregular sleep to metabolic conditions and heart health, its association with incident dementia remains unclear.
In the latest research, scientists evaluated the health data of more than 88,000 people in the UK, with an average age of 62, following them for an average of seven years.
The researchers calculated their sleep regularity – their daily consistency in sleep-wake patterns – based on data from a wrist-worn device the participants wore that measured their sleep cycle for about a week.
They estimated the probability of participants being in the same sleep state – asleep or awake – at any two times 24 hours apart, averaged over the seven days.
Participants who slept and woke up at the same time every day had a sleep regularity index of 100, while those who slept and woke up at different times had a score of zero.
About 480 people in the study developed dementia.
When investigating the link between sleep regularity scores and the risk of dementia, scientists found that the risk of the neurological disease was higher for those with more irregular sleep.
Individuals in the lowest fifth percentile had the most irregular sleep, with an average score of 41, while the highest 95th percentile had the most regular sleep with an average score of 71.
Participants in these two groups had an average sleep regularity score of 60, the study noted.
“Based on our findings, people with irregular sleep may just need to improve their sleep regularity to average levels, compared to very high levels, to prevent dementia. Future research is needed to confirm our findings,” said Dr. Pase.
Citing the limitations of the research, the scientists said they cannot rule out that another unknown factor may play a role in the link between sleep regularity and dementia.
The study also does not prove that sleep irregularity causes dementia, but only shows an association, the researchers said.