The effect of a healthy night's sleep on brain health.
Sleep may feel like rest or “time when nothing happens”, but for your brain, sleep is actually an active maintenance period. During the night, your brain recovers, memories are consolidated, and waste products are cleared. Those who sleep poorly on a regular basis strain their brain night after night.
Large studies show that sleep plays a significant role in the risk of cognitive decline and dementia. Interestingly, it's not just about too little sleep. Both short sleep and very long sleep are associated with a higher risk. For most people, the best balance is around 7 to 8 hours of sleep per night.
As the evidence has strengthened in recent years, sleep has been added as an independent risk factor for dementia in the latest version of the LIBRA score (LIBRA2).
When it comes to sleep, it's not just about the number of hours, but several aspects at once:
Duration: consistently getting less than 6 to 7 hours, or conversely, more than 8 to 9 hours per night
Quality: frequently waking up, restless sleep, not feeling refreshed upon waking
Sleep disorders: such as insomnia, sleep apnea, or restless legs
Many people become accustomed to poor sleep and view it as "normal for their age." However, just because you're used to it doesn't mean your brain isn't affected.
Sleep affects your brain through various mechanisms.
1. Nightly brain cleaning
During deep sleep, the so-called glymphatic system becomes active. This system removes waste products from the brain, including proteins involved in Alzheimer’s disease. With chronically poor or short sleep, this cleaning process works less effectively.
2. Memory and learning
New information is processed and stored during sleep. Poor or fragmented sleep disrupts this process, which you may notice as forgetfulness, concentration problems, and a "brain fog" feeling.
3. Emotions and stress
Insufficient sleep activates the stress system more. People become more irritable, worry more, and recover less well from emotional strain. Prolonged stress and elevated stress hormones are unfavorable for brain health.
4. Effect on other risk factors Poor sleep influences hormones that regulate hunger, blood sugar, and blood pressure. As a result, sleep deprivation indirectly increases the risk of diabetes, high blood pressure, obesity, and depression—all known risk factors for cognitive decline.
“I can function just fine on five hours of sleep.”
Many people feel accustomed to little sleep, but objective tests show that attention, reaction time, and memory decline even with mild sleep deprivation, even if you do not notice it immediately.
“I can catch up on my sleep debt over the weekend.”
Large differences between weekdays and the weekend disrupt your biological clock. This so-called “social jet lag” is associated with poorer health and more fatigue.
“A nightcap helps me sleep.”
Alcohol may speed up falling asleep, but it makes sleep lighter and disrupts REM sleep. On balance, you get less restorative sleep.
“Sleeping for a long time is always healthy.”
Sleeping for a very long time can sometimes be a signal of underlying problems, such as depression, inflammation or chronic illness. It is not automatically protective.
You don't need to become a perfect sleeper. Small, consistent adjustments make a difference.
1. Keep regular times
Try to go to bed and wake up at the same time every day
Keep the difference between weekday and weekend small (maximum one hour)
2. Build a calm evening routine
Reserve 30 to 60 minutes to unwind:
Dim bright lights and reduce screen use
Engage in calming activities like reading, listening to soft music, or doing light stretching exercises
Avoid work emails, news, and discussions right before bed
3. Make your sleep environment brain-friendly
Dark, quiet, and cool (usually around 18 to 19 degrees Celsius)
Use your bed mainly for sleeping, not for working or watching TV
Limit caffeine after noon
4. Manage worrying differently
Keep a notepad by your bed and jot down thoughts briefly
Try a simple breathing exercise:
Inhale for 4 counts
Exhale for 6 counts
Pause briefly
Repeat this for a few minutes
5. Take persistent sleep problems seriously
Discuss with your doctor if you:
Snore loudly or have breathing pauses
Feel extremely sleepy during the day
Experience prolonged poor sleep despite good habits
Treating sleep disorders often improves not only sleep quality but also mood, energy, and daily functioning.
If you suspect sleep apnea
If you have severe or long-term insomnia
If you have sleep problems combined with depression, anxiety, or memory complaints
Targeted treatment, such as cognitive behavioral therapy for insomnia, is often found to be more effective and sustainable in research than prolonged use of sleep medication.
At Remind, we've gathered the 15 most important modifiable factors for you. You can view each one individually and read about ways to manage them:
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