What Happens to Your Brain When You Sleep?

A good night’s rest is good medicine

Christine Richmond

Updated September 18, 2025

Tom Merton/Getty Images

Do you find yourself waking more during the night or rising earlier in the morning? These changes in sleep patterns are normal, although they may make it harder to get a good night’s sleep, according to AARP’s Global Council on Brain Health report The Brain–Sleep Connection. Still, “sleep is vital to brain health, including cognitive function,” according to the GCBH. What to do?

Think of sleep as a superpower you need to protect. It’s one of the six pillars of brain health. All adults, including people age 60 and older, need at least seven hours of shut-eye each night, according to the Centers for Disease Control and Prevention. While you snooze, some remarkable things happen inside your brain.

Toxins get flushed out

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 the most common form of dementia, Alzheimer’s disease, amyloid beta gradually clumps together to form amyloid plaques.

In a study that followed 189 cognitively healthy adults age 60 and older for up to six years, those who averaged fewer than six hours of sleep per night — especially those at higher genetic risk for Alzheimer’s — accumulated amyloid beta at a faster rate than those who got six to eight hours each night. The buildup of amyloid beta can happen years before symptoms of cognitive decline begin to show, according to the researchers, who published their results in Alzheimer’s & Dementia in 2024.

Memories are consolidated

Memory consolidation is an important part of learning: It’s when new, short-term memories are moved to a different region of the brain and converted into long-term memories. Much of that process happens during slow-wave sleep, according to a review of research focused on sleep, memory consolidation and aging that was published in Revue Neurologique in 2023. The authors analyzed brain imaging studies and concluded that changes in sleep patterns in older adults “can contribute to the disruption of the consolidation process during sleep and thus lead to cognitive impairment.” All the more reason to keep track of your sleep patterns and to see your doctor if you have persistent sleep troubles.

Legal Disclaimer

Best Of

Hormones are kept in balance

Hormones control everything from your metabolism to your mood, and good-quality sleep helps keep them balanced. For example, leptin and ghrelin, two hormones that regulate appetite, naturally rise and fall during different stages of sleep. Not getting enough shut-eye can disrupt this process, “which may explain the link between sleep deprivation and obesity,” according to a review of research published in Diabetology & Metabolic Syndrome in 2025.

“Disrupted sleep patterns can lead to hormonal imbalances that may accelerate the aging process and increase the risk of age-related diseases,” according to a research review published in Ageing Research Reviews in 2024. This can also increase a person’s risk of mood disorders, the authors note. People with poor-quality sleep were nearly seven times more likely to have depression than those who slept for seven to nine hours per night with no trouble sleeping in a study of 5,636 adults age 60 and older published in BMC Geriatrics in 2025.

It’s a myth that older adults need less sleep, but it’s true that aging can affect your ability to get a good night’s rest. If catching your nightly z’s becomes a struggle, be sure to ask your doctor about treatment options.

Learn more about how to get restorative sleep and take our challenge “Make Sleep Your Superpower.” Then dig into Staying Sharp’s other pillars of brain health: Eat Right, Manage Stress, Engage Your Brain, Ongoing Exercise and Be Social.