Medically reviewed by Kathleen Daly, MD
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- Older people often have sleep challenges, but they may benefit from seven to eight hours of sleep as much as younger adults.
- While you sleep, the brain performs important tasks for your day-to-day functioning and long-term cognitive health.
- Chronically reduced and poor-quality sleep in midlife and beyond may increase risks of cognitive decline and even neurodegenerative conditions like Alzheimer’s.
Poorer sleep can be both a symptom and a cause of cognitive aging, but you can take steps to improve your sleep and your long-term brain health.
Sleep Changes With Age
As people age, sleep patterns tend to change. This process begins during midlife and becomes more pronounced as you get older. Older adults may experience these two changes to their sleep:
- Different sleep-wake times: Older adults often go to bed earlier and wake up earlier. They also tend to have more trouble falling asleep. Overall, they get fewer total hours of sleep per night, which means they are less likely to get the full recommended seven to nine hours of sleep.
- Lower sleep quality: Older adults tend to spend less time in the deepest and most restorative stages of sleep, and they wake up more frequently at night.
Why these changes happen: Some of the sleep changes may be from normal brain changes. But certain factors, such as medications, chronic pain, and conditions like sleep apnea or restless legs syndrome, make it harder for some older individuals to sleep.
Do Older Adults Need as Much Sleep?
Some researchers think that older people may not need quite as much sleep as younger adults, especially if they are getting good-quality sleep. However, others think the reduced sleep is more of a symptom of aging and that older people would still benefit from getting enough high-quality sleep.
The Short Term: How Poor Sleep Can Lead to Worse Cognitive Function
Sleep deprivation affects how well your brain functions. Not getting enough high-quality sleep can negatively affect your:
- Concentration and attention
- Ability to form new memories
- Sensory and motor skills
- Emotions
- Impulse control
Fortunately, these changes are reversible when you get enough sleep. While some older folks might think decreased cognitive function is from irreversible cognitive aging, some changes might actually be from not getting enough high-quality sleep.
The Long Term: How Poor Sleep Contributes to Cognitive Aging
Sleep researchers believe that chronic poor sleep may negatively impact your long-term brain health, increasing risks of both mild cognitive decline and severe neurodegenerative conditions like Alzheimer's disease.
Here's how not getting enough sleep or enough high-quality sleep can affect your cognitive health in the long term:
- Not getting enough sleep: One study that included more than 800,000 women around the age of 60 found that getting less than seven hours of sleep per night was associated with a slightly increased risk of dementia in the next 20 years. Another study that tracked more than 5,600 older adults found that, on average, people with sleep issues performed worse at several cognitive tests. Their performance also declined more steeply over the next four years.
- Not getting enough high-quality sleep: Deep phases of sleep are especially beneficial. People who generally feel restored and rested after waking are less likely to experience cognitive decline and dementia. Sleep fragmentation is a related factor. One study of people in their mid-30s to late-40s found that people with very fragmented sleep performed worse on cognitive tests a decade later.
A Two-Way Street
The relationship between sleep and cognitive decline goes both ways. Chronic poor sleep seems to increase your risk of cognitive decline and even dementia. However, the reverse is also true.
In people with mild cognitive decline, sleep disorders are common. In those with dementia, sleep issues are even more common and severe, partly due to irreversible changes to the brain. This can create a negative feedback loop. Decreased sleep worsens cognitive functioning both short- and long-term, but decreased cognitive functioning can make it harder to get good sleep.
This makes it even more important to value sleep in midlife and older adulthood to help prevent this negative cycle.
Importance of Sleep for Your Brain
While you sleep, your brain performs many important functions for your overall cognitive health. Here are two main benefits to your cognitive health that sleep allows for:
1. Waste Removal
The brain has its own waste-removal system known as the glymphatic system. This network of fluid-filled channels flushes out toxic proteins while you sleep, much like a dishwasher running at night.
Some of these proteins are the same ones that build up in the brains of people with Alzheimer’s disease. The glymphatic system is much better at getting rid of the proteins while you sleep, especially during deep sleep.
People who have poorer function of the glymphatic system have a higher risk of developing dementia. In people with reduced or poorer sleep, the brain isn’t as good at clearing these abnormal proteins at night. This may be part of why poorer sleep in midlife and beyond might increase your risk of later dementia.
2. Anti-inflammatory Effects
Getting enough sleep helps minimize inflammation. In people of all ages, chronic sleep deprivation tends to increase inflammation, which can affect the brain.
Long-term, inflammation may increase your risk of neurodegenerative conditions like Alzheimer’s. To a lesser extreme, long-term inflammation might also increase the risk of mild cognitive decline with age. Getting enough quality sleep may help lower this inflammation and decrease these risks.
Next Steps
Assess your sleep habits and prioritize your time to get seven to nine hours of sleep per night. Learn about strategies to improve your sleep, like reducing caffeine, getting regular exercise, and keeping your room cool at night. Work with a healthcare provider to address any medical conditions interfering with your sleep.
