Donepezil, a medication commonly prescribed for Alzheimer’s disease and other cognitive disorders, **can cause insomnia and sleep disturbances, including sleepwalking** in some patients. While not everyone experiences these side effects, there is documented evidence that a subset of individuals taking donepezil report trouble sleeping, vivid or abnormal dreams, nightmares, and even parasomnias such as sleepwalking and sleep-talking.
The underlying reason for these sleep-related side effects is linked to donepezil’s mechanism of action. Donepezil works by inhibiting acetylcholinesterase, an enzyme that breaks down acetylcholine in the brain. By increasing acetylcholine levels, it enhances communication between nerve cells, which can improve memory and cognition. However, acetylcholine also plays a significant role in regulating sleep cycles, particularly REM (rapid eye movement) sleep, the stage of sleep where dreaming occurs. Increasing acetylcholine activity can intensify REM sleep, potentially leading to more vivid dreams, nightmares, and disruptions in normal sleep patterns.
Clinical observations and patient reports have shown that about 3% of patients on donepezil experience abnormal dreams. Moreover, nearly half of patients who take donepezil at night report nighttime disturbances such as insomnia, vivid dreams, nightmares, sleepwalking, sleep-talking, and even nighttime psychosis. These disturbances appear to be more common when the medication is taken in the evening rather than in the morning. Some healthcare providers suggest switching the timing of donepezil administration from night to morning to reduce these sleep-related side effects before considering changing the medication altogether.
Insomnia caused by donepezil can manifest as difficulty falling asleep, frequent awakenings during the night, or waking up too early and being unable to return to sleep. This can lead to daytime fatigue and reduced quality of life. Sleepwalking and other parasomnias, although less common, are more concerning because they involve complex behaviors during sleep that the person is not fully aware of, which can pose safety risks.
Other common side effects of donepezil include nausea, diarrhea, loss of appetite, muscle cramps, and fatigue. Serious side effects, though rare, can include irregular heartbeat, severe dizziness, seizures, and gastrointestinal bleeding, but these are unrelated to sleep disturbances.
Patients experiencing insomnia or unusual sleep behaviors while on donepezil should discuss these symptoms with their healthcare provider. Adjusting the time of dosing, lowering the dose, or in some cases switching to a different medication may be necessary. It is important not to stop donepezil abruptly without medical advice, as this can worsen cognitive symptoms.
In summary, donepezil **can cause insomnia and sleepwalking** due to its effects on brain chemistry and sleep regulation. These side effects are more frequently reported when the drug is taken at night, and managing the timing of the dose can often help mitigate them. Patients and caregivers should monitor sleep patterns closely and communicate any concerns to their healthcare team to ensure safe and effective treatment.
