Lack of sleep may be a symptom of age-related cognitive decline, and even one of its causes, but you can take steps to improve your sleep and brain health in the long term.

Lack of sleep negatively affects several key aspects:

Brain aging: Lack of sleep in midlife is linked to a decline in mental abilities and accelerated brain aging.

Impaired cell regeneration: Deep sleep is the primary time when the body secretes growth hormones to repair tissues and cells.

Declining skin health: Lack of rest leads to increased levels of the stress hormone (cortisol), which breaks down collagen responsible for skin elasticity and youthfulness.

Age-related diseases: Chronic insomnia increases the risk of type 2 diabetes, heart disease, and high blood pressure.

Sleep changes with aging

As we age, sleep patterns tend to change. This process begins in midlife and becomes more pronounced with aging. Older adults may experience two changes in their sleep, according to 'Health' website:

1- Difference in sleep and wake times: Older adults often sleep earlier and wake up earlier. They also have more difficulty falling asleep. Overall, they get fewer hours of sleep per night, meaning they are less likely to get the recommended 7 to 9 hours of sleep.

2- Decreased sleep quality: Older adults tend to spend less time in deeper, more restorative sleep stages and wake up more frequently during the night.

Reasons for these changes:

Some sleep changes may result from natural brain changes. But factors such as medications, chronic pain, and conditions like sleep apnea or restless legs syndrome make sleep more difficult for some older adults.

Short-term: How does lack of sleep lead to cognitive decline?

Sleep deprivation affects brain efficiency. Not getting enough good sleep can negatively impact:

Concentration and attention.

Ability to form new memories.

Sensory and motor skills.

Emotions.

Impulse control.

Fortunately, these changes can be reversed once adequate sleep is obtained. While some older adults may think that cognitive decline is due to irreversible cognitive aging, some changes may actually be due to not getting enough good sleep.

Long-term: How does lack of sleep contribute to cognitive decline with aging?

Sleep researchers believe that chronic lack of sleep may negatively affect brain health in the long term, increasing the risk of mild cognitive decline and severe neurodegenerative diseases such as Alzheimer's.

Here is how not getting enough sleep, or not getting good sleep, affects your cognitive health in the long term:

One study involving more than 800,000 women around age 60 found that getting less than 7 hours of sleep per night is associated with a slight increase in the risk of dementia over the following 20 years.

Another study tracking more than 5,600 older adults found that people with sleep problems, on average, performed worse on many cognitive tests. Their performance also declined sharply over the following 4 years.

Not getting enough good sleep: Deep sleep stages are particularly beneficial. People who generally feel refreshed and rested upon waking are less likely to experience cognitive decline and dementia.

Sleep disruption is a relevant factor; one study conducted on people aged mid-30s to late 40s found that those with severe sleep disruption performed worse on cognitive tests a decade later. Hence, sleep becomes increasingly important in midlife and for older adults to help prevent this vicious cycle.

The importance of sleep for your brain

During sleep, your brain performs many important functions for your overall cognitive health. Here are two main benefits of sleep for your cognitive brain health:

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 during sleep, much like a dishwasher running at night.

Some of these proteins are the same ones that accumulate in the brains of Alzheimer's patients. The 'glymphatic system' is exceptionally efficient at removing these proteins during sleep, especially during deep sleep.

People with impaired glymphatic system function are more prone to dementia. And in people who suffer from lack of sleep or poor sleep, the brain is unable to efficiently clear these abnormal proteins during the night. This may be one reason for the increased risk of dementia later in life with lack of sleep in midlife and beyond.

2- Anti-inflammatory effects

Getting enough sleep helps reduce inflammation. In people of all ages, chronic sleep deprivation tends to increase inflammation, which can affect the brain.

In the long term, inflammation may increase the risk of neurodegenerative diseases such as Alzheimer's.

To a lesser extent, chronic inflammation may also increase the risk of mild cognitive decline with aging. Getting enough good sleep may help lower this inflammation and reduce these risks.

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