3 Things to Know About Sleep and Your Brain

Do you find yourself waking more during the night, or rising earlier in the morning? These changes in sleep patterns are normal, according to AARP’s Global Council on Brain Health report “The Brain–Sleep Connection.” Aging can affect your ability to get a good night’s sleep, yet “sleep is vital to brain health, including cognitive function,” according to the report. Here are three things you should know about catching your nightly z’s.

1. It’s a myth that older adults need less sleep.

Older adults need about the same amount of sleep as all adults do — at least seven hours — according to the Centers for Disease Control and Prevention. Yet sleep disturbances become more common with age. For example, older adults tend to get less REM sleep, according to a review article on the subject published in The Permanente Journal in 2022. REM is the sleep phase in which your eyes twitch, your brain is active and you’re most likely to dream. It’s believed to play a role in memory consolidation.

2. While you sleep, your brain is busy purging toxins.

During a phase of deep sleep known as slow-wave sleep, your brain fires up what’s called the glymphatic system for a nightly self-clean. The glymphatic system uses cerebrospinal fluid to flush out toxins and waste products, such as amyloid beta. In Alzheimer’s disease, amyloid beta gradually clumps together to form amyloid plaques. In a study published in JAMA Neurology in 2023, getting less slow-wave sleep was associated with an increased risk of dementia among 346 participants with an average age of 69 years. A review of research published in Biomedicines in 2023 explored the relationships between the glymphatic system, aging, memory and sleep. Its authors concluded that, although more research is needed, “until then, getting a good night’s sleep is the most reliable way to maintain effective glymphatic clearance.”

3. Your sleep quality can have a big effect on your mood.

Being sleep-deprived or getting too much sleep can dampen your mood, according to a meta-analysis published in Frontiers in Physiology in 2023. Researchers analyzed six studies involving 33,595 middle-aged and older adults, following them from three to nine years. They concluded that getting seven hours of sleep was associated with the lowest risk of depression. And in a sleep study of 36 people average age 72, those who had fallen asleep but then spent more of the night hours awake were more likely to report a depressed mood, as reported in Psychological Medicine in 2022. 

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