Sleep plays a key role in attention, memory, and overall brain health. In recent years, research has found that chronic sleep problems such as sleep deprivation and poor sleep quality or quantity are linked to a higher risk of dementia, including Alzheimer’s disease.

“Poor sleep isn’t just about feeling tired — it can actually affect how your brain ages,” says Raj Dasgupta, MD, a board-certified internal and sleep medicine specialist at Huntington Health in Pasadena, California. And the relationship isn’t one-way: Sleep disorders may contribute to dementia risk, and they can also show up early as dementia develops.

When you understand this connection it may help you better support your sleep and long-term brain health.

Research findings strongly link sleep issues and dementia. In one study of nearly 8,000 adults, people ages 50 to 70 who regularly slept less than six hours per night had a 30 percent higher risk of developing dementia than those who slept the seven hours or more recommended by the Centers for Disease Control and Prevention (CDC).

hat said, researchers don’t yet know if poor sleep directly causes dementia, says Michelle Jonelis, MD, a board-certified sleep medicine physician at Lifestyle Sleep in Mill Valley, California. In some cases, sleep problems may be an early sign of dementia onset.

 But scientists have discovered a few plausible mechanisms. 

During deep, slow-wave sleep, the brain clears waste proteins like amyloid and tau — by-products of normal brain activity that can build up during waking hours. When sleep is too short or frequently interrupted, the brain may not perform this “cleaning” as effectively, says Dr. Dasgupta. Over time, if these proteins aren’t removed efficiently, they can clump together and form the plaques and tangles characteristic of Alzheimer’s disease.

A shortage of rapid eye movement (REM) sleep, which is the final stage of sleep and supports memory and emotional processing, may also contribute, Dasgupta notes. Emerging research supports this idea: In one long-term study of middle-aged adults, individuals who spent less time in REM sleep exhibited more shrinkage 13 to 17 years later in the parietal lobe, a brain region that is particularly vulnerable to Alzheimer’s disease.

The bottom line: Sleep problems don’t automatically lead to dementia, but consistently poor, disrupted, or untreated sleep may increase risk over time, making healthy sleep a worthwhile goal for brain health.

Sleep changes are common in people with dementia. That’s because dementia often throws off the body’s circadian rhythm, or the internal clock that regulates sleep, says Dasgupta. “People may wake up often, nap more, or become restless and confused in the evening,” he notes, a pattern sometimes referred to as sundowning.

Dr. Jonelis explains that these sleep disruptions can begin early in dementia, even before memory symptoms are apparent.

 As dementia progresses, factors such as reduced social interaction and lower activity levels