Taking long naps could be an early sign of Alzheimer’s disease, according to a team of scientists who tracked the daytime sleeping habits of elderly people as part of a study. The findings suggest that an increase over time in naps was linked to a higher chance of developing mild cognitive impairment or Alzheimer’s.
The scientists believe it is more likely that excessive napping could be an early warning sign, rather than it causing the mental decline. Dr. Yue Long, an assistant professor of psychiatry at the University of California San Francisco, said, “It might be a signal of accelerated ageing. The main takeaway is if you didn’t use to take naps and you notice you’re starting to get more sleepy in the day, it might be a signal of declining cognitive health.”
The team tracked more than 1,000 people, with an average age of 81, over several years. Each year, the participants wore a watch-like device to track mobility for up to 14 days. Each prolonged period of non-activity from 9 am to 7 pm was interpreted as a nap. The participants also underwent tests to evaluate cognition each year. At the start of the study, 76 per cent of participants had no cognitive impairment, 20 per cent had mild cognitive impairment, and four per cent had Alzheimer’s disease.
The research said that for participants who did not develop cognitive impairment, daily daytime napping increased by an average of 11 minutes a year. The rate of increase doubled after a diagnosis of mild cognitive impairment to a total of 24 minutes and nearly tripled to a total of 68 minutes after a diagnosis of Alzheimer’s disease.
Overall, participants who napped more than an hour a day had a 40% higher risk of developing Alzheimer’s than those who napped less than an hour a day; and participants who napped at least once a day had a 40% higher risk of developing Alzheimer’s than those who napped less than once a day. The scientists said feeling increasingly drowsy during the day could be an early sign that changes were underway in the brain.
