A new study has revealed that individuals who experience more interrupted sleep in their 30s and 40s are at a significantly higher risk of developing memory and thinking problems later in life. The research, conducted by experts from the University of California, San Francisco, tracked the sleep quality of hundreds of participants over the course of a year, and then assessed their cognitive ability more than a decade later.

Using a wrist activity monitor, researchers measured the sleep quality of the participants during two overnight visits, gathering data for a total of six nights per person. Sleep fragmentation, characterized by short and repetitive interruptions of sleep, was determined by tracking the amount of sleep obtained and periods of movement during sleep. The average age of the participants at this stage of the study was around 40 years old.

The cognitive abilities of 526 participants were evaluated between 2015 and 2016, more than a decade later, using standardized interviews and cognitive tests that assessed processing speed, executive function, memory, and fluency. The findings revealed a significant correlation between sleep fragmentation and poor cognitive performance.

On average, study participants slept for about six hours per night, with approximately one-fifth of their sleep time being disrupted. The study demonstrated that individuals with higher sleep fragmentation or more time spent in movement during sleep were more likely to receive poor cognitive scores on all the tests conducted ten years later.

Further analysis found that out of the 175 individuals experiencing the most disrupted sleep, 44 exhibited poor cognitive performance a decade later. In comparison, only 10 out of the 176 individuals with the least disrupted sleep faced cognitive difficulties. Factors such as gender, race, BMI, as well as a history of depression or hypertension were associated with lower sleep quality and increased sleep fragmentation.

Dr. Yue Leng, an associate professor of psychiatry at the University of California, San Francisco and a study author, emphasized the importance of understanding the connection between sleep and cognition earlier in life. With signs of Alzheimer's disease appearing in the brain years before symptoms manifest, recognizing sleep problems as a risk factor for the disease is crucial for preventive measures.

In the study, participants were also asked to maintain sleep diaries, recording bedtimes, wake times, and self-rating sleep quality. Surprisingly, the subjective assessments and objective measures of sleep duration did not correlate with midlife cognition.

The study highlights the significance of prioritizing sleep health and obtaining quality sleep. The Centers for Disease Control and Prevention (CDC) recommends that individuals should aim for seven to ten hours of sleep per night, depending on their age. However, one in three Americans does not meet this requirement. Additionally, sleep disorders such as sleep apnea, insomnia, and restless leg syndrome affect 50 million to 70 million Americans, leading to further sleep disruptions.

Disrupted sleep is considered a public health problem by the CDC due to its association with a higher risk of various conditions including diabetes, stroke, cardiovascular disease, and dementia. Another recent study revealed that individuals who frequently struggle to fall asleep have a 49% increased risk of dementia, while those who frequently wake up during the night and experience difficulty falling back asleep face a 39% increased risk.

Dr. Leng emphasizes the need for more research to assess the link between sleep disturbances and cognition at different stages of life. Identifying critical periods when sleep has a stronger association with cognition could present opportunities for preventing Alzheimer's disease and other cognitive impairments later in life.

As the link between interrupted sleep and cognitive health becomes clearer, individuals and healthcare professionals should pay increased attention to sleep quality and prioritize adequate, uninterrupted rest as an important aspect of overall well-being.