Frequent nighttime awakenings linked to slowed brain function

Scientists have proven that it is specifically fragmented sleep — frequent nighttime awakenings and prolonged periods of wakefulness — that is associated with slower information processing and impaired working memory in older adults. The results of the study were published in the journal Sleep Health: Journal of the National Sleep Foundation.

Sleep plays a key role in maintaining brain health. During nighttime rest, the body repairs tissues, regulates hormones, and strengthens the immune system, while the brain organizes information received during the day and consolidates memories. However, not only the duration of sleep matters, but also its quality.

In the new study, scientists analyzed data from the Einstein Aging Study, a project dedicated to aging and cognitive health. The analysis included 261 people over the age of 70 with no signs of dementia. The average age of participants was 77 years.

Over the course of 16 days, participants wore actigraphs on their wrists — devices that record movements and allow for the assessment of sleep-wake cycles. Simultaneously, they completed brief cognitive tests on smartphones six times a day. These tasks assessed information processing speed, visuospatial working memory, and the ability to associate objects with their visual features.

The results showed that people who were awake more frequently during the night after falling asleep, on average, demonstrated slower information processing speed and poorer working memory performance. They also showed a reduced ability to integrate visual details into a unified picture — an important element of memory formation.

"The effect was evident even at a short-term level. After nights with a greater number of awakenings, participants performed information processing speed tasks noticeably worse the following day than usual. These findings show that sleep fragmentation can directly affect brain function as early as the next day," the researchers concluded.

The scientists also note that a better understanding of these short-term effects may help identify individuals who would benefit from early intervention for sleep disturbances to prevent further cognitive decline. The authors added that the study was conducted among older adults, so the impact of sleep quality on cognitive function in other age groups may differ.