Sleep is the time when the body actively restores and strengthens its resources. During our deepest sleep, muscles are relaxed, allowing them to rest and be repaired. The blood supply to muscles is increased, bringing hormones and other chemicals to repair damage and normal wear and replacing the proteins needed to fuel movement.
A Circadian clock controls when these activities and other regular ones occur. From its control center very near the brain's visual cortex, it secretes various hormones at given times throughout the day and night. (Circadian is Latin for "about a day.") The hormones trigger a person to feel sleepy or hungry. Once asleep, they trigger the brain when to go into a heavy sleep where various cleaning, repair and other upkeep tasks happen, when to go into a lighter sleep (REM sleep) where memory sorting dreams occur, and when to wake up.
The internal clock maintains its accuracy in a variety of ways, but the most important is by using information from light sensors in the eyes sent via the visual cortex's non-visual sensory system. When the clock is damaged by dementia, its functioning can become inaccurate and garbled. Sleep and waking routines are disrupted. A person might get their days and nights turned around. More likely, they will wake up several times a night and nap often during the day. Of course, it is not only the PlwD's* sleep that is disturbed. The care partner's sleep is too.
The control centers for both visual and non-visual systems are very close together in an area that is often an early LBD target (think illusions, hallucinations and the like). Because of the closeness, the Circadian clock can be an early target as well, causing any of the above time regulation issues.
Of course, Lewy bodies are the only culprits. As people age, they tend to wake more often for a variety of reasons, from bathroom visits to apnea and more. The circadian clock functions in cycles of about 90 minutes each. Waking in the middle of a cycle can interfere and cause the clock to malfunction. This may cause a person to have difficulty sleeping at night, staying awake during the day or have repeated shorter periods of sleeping and waking throughout the day. None of these may provide for the deep sleep or for the dreaming sleep, both of which the brain needs for good functioning.
Circadian clock malfunctioning can cause a person to sleep a lot in the daytime, but there are other reasons for this too. With dementia, everything from thinking to moving takes more time--and more energy. Add the tremors common with PDD*, and it gets even more energy-intensive. This means that the PlwD needs more sleep to replenish their energy. It's nature's way of allowing the body and the brain the time they need to catch up and clean up. Unless the PlwD is not sleeping much at night, this is not something to stress about. Just use the time to do something for yourself--like catching up on your own sleep!
If the PlwD isn't getting much night-time sleep, experiment with nap time and bedtime routines to find the best ones for helping a PlwD fall asleep at night and stay asleep for longer periods at night. (Suggestions in a later blog.)
Next week: Sleep, Part 3: The Brain's Janitor.
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LBD: Lewy body dementia
PD: Parkinson's disease
PlwD: person living with dementia
DLB: dementia with Lewy bodies
PDD: Parkinson's disease with dementia
PlwD: person/people living with dementia
PlwPD, LBD, PDD, etc.: person/people living with PD, LBD, PDD, etc.
MCI: mild cognitive impairment
MCI-LB: the form of MCI that precedes LBD
BPSD: behavioral and psychological symptoms of dementia
A Caregivers’ Guide to Lewy Body Dementia
Managing Cognitive Issues in Parkinson's and Lewy Body Dementia
Helen and James Whitworth are not doctors, lawyers or social workers. As informed caregivers, they share the information here for educational purposes only. It should never be used instead of a professional's advice.