Sleep changes in dementia: Why do people with dementia sleep a lot?

Sleep Changes In Dementia

People with dementia usually spend a lot of time sleeping both during the day and night, especially in the late stages of the disease. The sleep pattern typically changes as a person ages. However, these changes are more complex in people with Alzheimer’s disease or other forms of dementia.

As the disease advances, brain damage becomes widespread. The person also becomes weaker over time and, as a result, may feel exhausted after performing the simple routine tasks such as eating, communicating, or trying to comprehend their surroundings can exhaust them. As the symptoms worsen, they may need to sleep more during the day. Some drugs, including antidepressants, antipsychotics, antihistamines, and sleeping pills, may also cause sleepiness.

Why does Alzheimer’s disease or dementia affect sleep?

Although sleep disorders are common for people with dementia, how the disease affects sleep is still not clearly understood. Sleep disturbances may foreshadow the cognitive decline that occurs in dementia patients. Commonly occurring sleep problems include:

  • sleeping during the day and being awake and agitated at night
  • waking up more frequently and staying awake longer at night
  • experiencing disorientation in the dark if the person wakes up to use the toilet
  • unable to distinguish between day and night
  • waking up in earlier hours and mistakenly believing that it is daytime.

Experts believe that Alzheimer’s disease and other types of dementia cause cellular changes in the brain that can disturb the sleep-wake cycle. In some people, the damage to their internal biological clocks (that judge the time) may lead to sleepiness at the wrong time of the day. Furthermore, malfunctioning of some other parts of the brain (that control whether we stay awake or not) due to damage may also result in sleep disturbances.

A person with dementia may occasionally entirely reverse their sleep pattern, staying awake all night and sleeping all day.

What to do if the person with dementia is sleeping a lot?

Dementia progression is likely the cause if your late-stage dementia patient has gradually started to sleep a lot. However, if it has suddenly started, or the person does not feel well in other ways, it may be due to some other reason.

In the latter case, you should consult a doctor to rule out any infection or condition that could be causing sleep disturbances in the patient. It would also be helpful to ask the doctor or the pharmacist about the side effects of the medication that your patient might be using.

If the person does not seem distressed or uncomfortable, there is no reason to be worried about sleeping more during the day. However, lying down and sleeping most of the time may cause health problems. Therefore, it is essential to check on your patient to ensure they do not develop any physical health issues.

Sleep disturbances in people with Lewy body dementia and Parkinson’s disease dementia

The type of dementia may affect the sleep pattern of dementia patients. People with Lewy body dementia (LBD) or Parkinson’s disease dementia often experience sleepiness during the day but feel very agitated and disturbed at night. They may hallucinate, feel confused, and have nightmares. Furthermore, they usually exhibit symptoms like insomnia, sleep apnea (breathing problems), and restless legs.

People with these types of dementia also manifest rapid eye movement (REM) sleep disorder at the earliest stages of the disease and onwards. This disorder causes them to mistakenly act out their dreams by shouting or moving in bed and can injure themselves or their sleeping partners. As a result, the person feels like they have not slept at
all, making them exhausted and sleepy during the day.

It might be difficult to stay awake throughout the day following a bad night’s sleep. However, if feasible, try to limit daytime sleep to tiny bursts or ‘catnaps.’ Otherwise, a person’s biological clock might become quite confused, making sleeping soundly at night even more difficult.

Brain proteins and sleep changes in Alzheimer’s disease

Recent research has shown a link between beta-amyloid protein, the hallmark of Alzheimer’s disease, and sleep changes. The brain removes excess beta-amyloid protein when a person sleeps. Sleep deprivation can cause an increase in beta-amyloid, as indicated in the mice model. In another study (performed on human subjects), the researchers found an increase in beta-amyloid levels increased up to 5% following a sleep deprivation of about 31 hours.

Scientists have also found a link between tau protein and sleep disturbances. According to a study, sleep deprivation of as little as one night can increase tau levels up to 50% in cerebrospinal fluid.

The link between beta-amyloid, tau, and Alzheimer’s disease is complicated, but researchers agree that getting quality sleep assists the brain in removing extra proteins. They are still uncertain if sleep disturbance causes Alzheimer’s, aggravates symptoms, and accelerates disease development or if it is a consequence of a disease.


1. National Institutes of Health, 2018. Sleep deprivation increases Alzheimer’s protein. NIH Research Matters, April, 24.

2. Shokri-Kojori, E., Wang, G.J., Wiers, C.E., Demiral, S.B., Guo, M., Kim, S.W., Lindgren, E., Ramirez, V., Zehra, A., Freeman, C. and Miller, G., 2018. β-Amyloid accumulation in the human brain after one night of sleep deprivation. Proceedings of the National Academy of Sciences, 115(17), pp.4483-4488.

3. Holth, J.K., Fritschi, S.K., Wang, C., Pedersen, N.P., Cirrito, J.R., Mahan, T.E., Finn, M.B., Manis, M., Geerling, J.C., Fuller, P.M. and Lucey, B.P., 2019. The sleep-wake cycle regulates brain interstitial fluid tau in mice and CSF tau in humans. Science, 363(6429), pp.880-884.

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