Variety of sleep and circadian rhythms of elderly dementia patients living in group home residences

In the present study, we investigated 70 elderly individuals with dementia residing in a group home in Japan (88.1 ± 6.6 SD years; 12 males and 58 females). Sleep measurements were collected via an accelerometer placed under the mattress from March 2021 to January 2024. The accelerometer-derived activity counts were transformed and plotted as actograms. On the basis of the actograms, sleep patterns were categorized into three groups: regular nighttime sleep (Type 1, n = 38, 54.3%), regular nighttime sleep with daytime naps (Type 2, n = 29, 41.4%), and irregular sleep (Type 3, n = 3, 4.3%). We compared accelerometer-derived sleep measures between the Type 1 and Type 2 groups due to the small number of participants in Type 3. Interestingly, Type 2 individuals had a significantly longer bed in time and total sleep time. However, their sleep onset latency, time of wakefulness after sleep onset and sleep efficiency did not differ from those of Type 1 individuals. Additionally, we assessed the relationships between sleep patterns and dementia characteristics, such as independence in daily living and level of care needed. No significant differences were observed in sleep measurements across these characteristics. To evaluate endogenous circadian rhythms, seven dementia patients (Type 1, n = 1; Type 2, n = 6) wore a patch-type wearable temperature sensor for approximately 24 h to estimate core body temperature (CBT). Although the zero-amplitude test revealed a significant rhythmicity in all patients, the CBT rhythms showed lower amplitude and unstable phases. In summary, our findings indicate that dementia patients display varying sleep patterns that are independent of dementia characteristics. The dysfunction of sleep homeostasis and entrainment of circadian pacemakers might be due to the light environment in the group home residence or impairment of the circadian clock itself in dementia patients.