Dementia is a progressive condition characterized by a decline in cognitive functions that interfere with daily life. Changes in sleep patterns, including excessive daytime sleepiness, are frequent complaints reported by caregivers. This increase in time spent sleeping, known as hypersomnia, is a common and expected development as the illness progresses. This article explores the reasons behind this increased need for sleep and when it signals a problem requiring immediate attention.
Sleep Patterns and Dementia Progression
Increased time spent sleeping is common in individuals with dementia, especially as they enter the middle to late stages of the disease. This excessive daytime sleepiness results from a disruption of the body’s natural internal timekeeper, the circadian rhythm. The brain’s ability to regulate the sleep-wake cycle becomes significantly impaired due to the disease process. This disruption leads to an irregular pattern where nighttime sleep is fragmented and poor in quality, while the person experiences an increased need for napping during the day. In the late stage of dementia, some individuals may sleep for most of the day and night.
Direct Neurological Causes of Increased Sleep
The primary reason for excessive sleepiness lies in the physical damage dementia inflicts on the brain’s sleep-regulating centers. The suprachiasmatic nucleus (SCN), which acts as the body’s internal clock, often suffers damage, particularly in Alzheimer’s disease. This leads to a loss of function in the areas that control when the person feels alert or sleepy. Furthermore, the pathological proteins associated with dementia directly damage wakefulness-promoting neurons in the brain. Research indicates that the accumulation of tau protein tangles is strongly linked to the degeneration of brain regions responsible for keeping a person awake.
The brain’s demand for rest, sometimes called “sleep pressure,” also increases significantly in a brain affected by dementia. Maintaining cognitive function and attempting to process information becomes an immense energy expenditure for a damaged brain. This constant, exhausting effort contributes to a general slowing of brain activity and a higher cumulative need for sleep. Studies have also linked higher levels of the protein beta-amyloid, a hallmark of Alzheimer’s, with increased daytime sleepiness.
Medication Side Effects and Other Contributing Factors
Not all excessive sleepiness is solely due to the progression of the disease itself, as other secondary factors frequently contribute to lethargy. A review of all medications is often warranted because several common drug classes used in dementia care can cause significant drowsiness.
Medications
These include antipsychotics, anti-anxiety medications like benzodiazepines, and certain antidepressants or sleep aids. Some medications, such as muscle relaxants or strong pain relievers like opioids, are known to cause excessive sedation, dizziness, and increased confusion in older adults. Even over-the-counter sleep remedies containing ingredients like diphenhydramine can worsen cognitive symptoms and contribute to daytime grogginess. Adjusting the dosage or timing of these drugs can often alleviate the side effect of hypersomnia.
Systemic Illnesses and Pain
Systemic illnesses, such as urinary tract infections (UTIs) or pneumonia, frequently present as sudden lethargy and increased sleepiness in older adults with dementia. Unlike in younger individuals, a fever may not be the most prominent sign of an infection. Unrecognized pain or discomfort can also cause a person to withdraw and sleep more as a coping mechanism. Conditions like depression, which often co-occurs with dementia, can manifest as a lack of energy and prolonged sleeping.
Signs That Require Immediate Medical Attention
While an increase in sleep is often expected with dementia progression, caregivers must know when this change crosses the line into a medical concern. Any sudden or dramatic increase in sleep time over a few days or weeks should be immediately evaluated by a doctor. For example, a patient suddenly sleeping 18 hours a day when they were previously sleeping 12 hours may signal an underlying issue. Difficulty rousing the patient, or an inability to wake them for meals or personal care, is a serious sign of distress. Caregivers should also look for accompanying symptoms such as a fever, new or increased confusion, sudden changes in mobility, or signs of pain. These symptoms, paired with excessive sleepiness, may indicate an infection, dehydration, or an adverse reaction to a medication that requires prompt assessment. Tracking the duration and timing of sleep before contacting a healthcare provider can provide important information for diagnosis and treatment.