How does dementia affect sleep?

A person with dementia may have problems with sleeping well or at the right times. Poor sleep may make the symptoms of dementia worse. Find out how dementia affects a person's sleep.

A person with dementia experiences physical changes in their brain because of their condition. These changes can affect how much, and how well they sleep.

A person with dementia may have problems with sleeping at night, and may sleep more during the day. They may find it difficult to get to sleep or they may wake up in the night. The person you care for may not feel well rested when they wake up.

Over time, if these problems happen often, poor sleep may make the symptoms of dementia worse. You may find this difficult to cope with.

Why is sleep important for health and wellbeing?

A person with dementia needs regular sleep to stay well. Most adults need between seven and nine hours of sleep a night. Sleeping well helps a person to be in a better mood, think more clearly, and maintain a healthy immune system. It can also help to prevent falls and accidents, and puts the body under less stress.

The two systems in the body that work together to control sleep are a person’s body clock and sleep pressure.

What is the body clock?

Our bodies sense natural light to know roughly what time of day or night it is. We also get a sense of time from routine daily activities – such as mealtimes, to create a sleep and wake cycle over 24 hours.

This tells our brains when it’s time to go to sleep (usually late in the evening) and when to wake up again (usually in the morning).

The body clock of a person with dementia may become damaged, making it harder for them to feel awake and alert during the day, and sleepy during the evening.

What is sleep pressure?

Sleep pressure is the increasing need to sleep after being awake for a long time. The longer a person has been awake for, the more likely that they will feel sleepy, and the more deeply they are likely to sleep. As a person sleeps, the pressure to sleep gradually wears off and they become more likely to wake up.

Some stimulants, such as caffeine, work by blocking the chemicals that make a person feel sleepy.

How do the body clock and sleep pressure work together?

It’s much easier for a person to get to sleep when they have built up lots of sleep pressure during the day, and their body clock senses that it’s evening. This turns on both sleep systems at the same time, and should make the person feel sleepy at the right time.

If the person doesn’t feel sleepy at night, their body clock may not be working well. They may also not have been awake for long enough to make the body need to sleep (for example, if they have taken a nap in the day).

Lifelong sleep patterns

Another factor that can affect a person’s sleep is patterns in their sleep during their lives. Some people will never have slept for long periods, and others may have had unusual sleeping patterns, such as working night shifts.

It may be very difficult for a person to change their lifelong sleeping patterns to suit other people, such as the daily schedule of a care home.

How will poor sleep affect health and wellbeing?

A person who doesn’t get enough good-quality sleep is likely to be tired, irritable, have a low mood and be less able to think clearly. It can also make them more likely to fall or have an accident. This can make caring for them more difficult.

If the stress of caring is making you unwell, talk to your GP. You should try to get as much good-quality sleep as possible. 

Looking after yourself as a carer

Good quality sleep is important for both carers and people living with dementia. Read our advice on looking after yourself as a carer.

Read advice

Why might a person with dementia not sleep well?

For a person with dementia, getting enough sleep can be a challenge. Sleeping well can be difficult for a person aged over 55, as the parts of the brain that control sleep may not work as well. An older person is likely to go to sleep earlier and may have difficulty sleeping through the night as much as they used to.

They may:

  • have difficulty getting to sleep
  • wake up several times during the night
  • sleep less deeply
  • sleep for less time overall.

As well as disruption to their body clock, a person with dementia may sleep more in the day and have difficulty sleeping at night. This process can start to happen even before a person has dementia, or if they have mild cognitive impairment (MCI).

Reasons for poor sleep may include:


It is common for a person with dementia to have other long-term health conditions, such as high blood pressure, diabetes or depression. Sometimes the drugs used to manage these conditions can also make a person’s sleep worse.

They may also have health conditions that regularly wake them up in the night, such as being in pain or having urinary problems that require going to the toilet often.


Dementia can affect the production of a sleep hormone in the brain called melatonin. This helps the person to feel sleepy when it gets darker in the evening. As a person’s dementia progresses, their brain may make less melatonin, which makes it harder to fall asleep in the evening.

This can be made worse by damage to the person’s body clock, which means melatonin levels don’t rise at the right time. Being in a bright environment during the day (particularly the morning), and a darker environment in the evening, can help to keep the sleep and wake cycle working as well as it can.

Being inactive and bored

A person with dementia can end up sleeping for long periods during the day if they don’t have enough meaningful physical, mental or social activity to keep them active and engaged.

You may find that they don’t feel tired enough to want to sleep at night and probably won’t sleep for very long if they do. Shorter sleeps tend to be lighter, so the person doesn’t get the benefit of a sustained, deep sleep lasting several hours.

For more information, see Keeping active and involved. For ideas for enjoyable and engaging activities, see The Activities handbook.

Being confused in the night

When a person with dementia wakes up during the night, they may feel anxious or confused, and not know what time it is. Instead of going back to sleep, they may believe it is time to start the day, or that they need to be somewhere to do something important.

For example, they may get dressed in the middle of the night in the belief that they need to get ready for work, or take their children to school. The person may try to go about an old routine, making breakfast and trying to leave the house for work.

It can be stressful for you, if the person is often awake and active during the night – particularly if you are worried that they might be doing something that isn’t safe. For more information see Changes in perception.

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