THIS IS YOUR BRAIN ON sleep
After a good night’s sleep, you feel alert and ready to tackle the day. But that’s not just because your brain has been resting. It has also been busy filing away memories and taking out the trash, so to speak, thanks to the glymphatic system, which washes the brain of waste materials. For example, a protein called betaamyloid, which is known to play a role in the development of Alzheimer’s, acts as a neurotoxin when it builds up, killing neural cells in the brain. But a good sleep removes excess beta- amyloid and other waste materials, says Dr. Liu-ambrose.
Because one of the common symptoms of Alzheimer’s is disrupted sleep, it’s unclear whether a lack of shut- eye should be considered part of the progression of the disease or a risk factor on its own, due to the buildup of beta- amyloids.
Nevertheless, poor sleep hastens your brain’s aging process— much like sitting in the sun sans SPF speeds up your skin’s aging process. And disturbed sleeping has been linked to all aspects of brain health, including an increased risk of depression and a decline in cognitive functions such as memory and reasoning. In one U. K. study out of University College London Medical School, middle- aged women who reported a drop in the average number of hours they slept had lower scores on cognitive tests involving reasoning and vocabulary.
What’s more, our central clocks— a. k. a. our circadian rhythms— can drift from the patterns of our childhood, making it hard to get that much- needed rest. “As we age, our central clock is less sensitive to stimuli like light, food and physical activity,” says Dr. Liu-ambrose; this change makes it harder to fall, and stay, asleep. We can also become more vulnerable to stress and anxiety, which further disrupt those rhythms.
One way to combat these fluctuations is to try what seasoned travellers do for jet-lag recovery: Get exposure to real daylight and eat your meals on time to nudge your brain into a routine. And don’t use bright screens at night, especially before bed, because they mimic sunlight and tell our circadian system that it’s day, not night—and, therefore, not time to sleep. Those who need more help might consider light therapies that have been developed to treat seasonal affective disorder, says Dr. Liu-ambrose.
The Takeaway: Many researchers consider six to eight hours of sleep a night to be the standard sweet spot, though this can vary by individual. If you’re routinely getting less than that and waking often in the night, not feeling refreshed in the morning and experiencing bouts of sleepiness during the day, talk to your doctor about sleep strategies— especially if you’re experiencing anxiety or depression. In the short term, napping can reverse some of the effects of poor sleep, including memory loss and increased stress. And you only need a 30- minute catnap to feel the results.