Good sleep does more than help you feel refreshed. It plays an important role in memory, thinking, learning and emotional wellbeing.
Poor sleep is linked to an increased risk of cognitive decline and dementia, making it important for healthy brain ageing.
Sleep supports brain health by helping the brain restore, repair, consolidate memories and clear waste products.
Why is sleep important for brain health?
Many people think sleep is a period when the brain "switches off". In reality, the brain remains highly active while we sleep, carrying out important maintenance and repair processes that support healthy ageing.
Sleep helps the brain:
- Consolidate memories and learning
- Improve concentration and thinking skills
- Maintain emotional wellbeing
- Repair and regenerate brain cells
- Clear waste products that build up during the day
These processes are essential for maintaining cognitive function as we get older.
Throughout the day, natural waste products build up in the brain as it works. During sleep, the brain activates a specialised cleaning system that helps remove some of this waste. Scientists believe this process, known as glymphatic clearance, may help protect brain health over time because some of the proteins cleared during sleep have been linked to dementia when they build up in the brain.
Deep sleep
During deep sleep, the body carries out important restoration and repair processes. Research suggests glymphatic clearance is particularly active during this stage of sleep.
REM sleep
Rapid Eye Movement (REM) sleep is the stage when most dreaming occurs. It is linked to memory, learning and emotional processing and plays an important role in cognitive restoration.
Both deep sleep and REM sleep are important, which is why sleep quality matters just as much as sleep quantity
Sleep and dementia risk
Growing evidence suggests that poor sleep is linked to an increased risk of dementia and cognitive decline. Sleep disturbances and untreated sleep disorders are associated with factors that may contribute to brain ageing. Research suggests sleep problems contribute to up to 15 per cent of Alzheimer's disease cases.
Research also suggests that successfully treating sleep disturbances may help delay the onset of cognitive impairment and improve cognitive function.
Could poor sleep be affecting you?
You may not be getting enough quality sleep if you:
- Regularly feel tired during the day
- Struggle with concentration or memory
- Need frequent daytime naps
- Wake feeling unrefreshed
- Take a long time to fall asleep
- Wake frequently throughout the night
How much sleep do adults need?
Most adults need around 7-9 hours of sleep each night
Individual needs vary, and waking more frequently during the night becomes more common as we age. However, healthy ageing does not mean sleep becomes less important. Quality sleep remains essential for maintaining brain function and wellbeing.
Rather than focusing only on the number of hours slept, ask yourself:
Do I feel rested, alert and able to function well during the day?
Six ways to improve sleep and support brain health
Going to bed and waking up at similar times each day helps regulate your body clock.
Exposure to natural morning light helps regulate the body's sleep-wake cycle and supports healthy melatonin production later in the day.
Aim for a bedroom that is:
- Cool
- Dark
- Quiet
- Comfortable
A sleep-supportive environment can improve sleep quality and reduce night-time disturbances.
Phones, tablets and televisions can interfere with the body's natural preparation for sleep. Reducing screen exposure before bedtime may help you fall asleep more easily.
Caffeine can remain in the body for hours and make falling asleep more difficult. Avoid caffeine within six hours of bedtime.
Alcohol may help you fall asleep initially but can disrupt sleep quality later in the night. Try avoiding alcohol four to six hours before bedtime.
Regular exercise is linked to better sleep and may help increase deep sleep. Try to avoid vigorous exercise close to bedtime. As a bonus, physical activity supports brain health in its own right.
When should you seek help?
Occasional poor sleep is normal. However, if sleep difficulties occur regularly or affect your daily life, speak with your GP.
Seek professional advice if you:
- Snore heavily or stop breathing during sleep
- Have persistent insomnia
- Feel excessively sleepy during the day
- Are concerned about your memory, thinking or concentration
- Notice changes in your mood alongside sleep problems
Sleep apnoea occurs when breathing repeatedly stops and starts during sleep. Symptoms may include loud snoring, gasping during sleep and excessive daytime tiredness. Untreated sleep apnoea has been associated with several health problems, including dementia.
Insomnia involves ongoing difficulty falling asleep, staying asleep, or waking too early. It can affect concentration, energy levels and mood, and may contribute to longer-term health problems if left untreated. Effective treatments are available, including cognitive behavioural therapy for insomnia (CBT-I).
The best age to start? Today.
When you improve sleep, the benefits start immediately. Quality sleep supports memory, learning and emotional wellbeing, and reduces the risk of cognitive decline and dementia. Prioritising sleep is a step you can take today to invest in your future brain health.
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