Scientists at the University of California found that that the duration and frequency of daytime sleep is associated with age. The researchers concluded that long daytime sleep increases the risk of developing dementia, writes the portal Sina.
The study involved 1.4 thousand volunteers, the observation lasted 14 years. In 75.7% of participants who did not have brain disorders, the duration of sleep increased by an average of 11 minutes per year. The risk of developing Alzheimer's disease became higher.
6 years after the start of the study, 24% of participants with normal cognitive development began to develop dementia. Scientists have linked this to long and frequent sleep. People who sleep more than an hour during the day are 40% more likely to develop Alzheimer's disease, experts have concluded.
Other research suggests that short naps are beneficial. Professor Huang Zhili of the Institute of Brain Science at Fudan University believes that naps of no more than 20 minutes during the day can «delay» brain decay.