Implementing changes to indoor environments, such as cooler bedrooms at night and increasing the amount of bright light during the day, could significantly improve sleep for people living with dementia, according to a study led by the University of Surrey.
The study, published in the journal Sleep, analysed more than 26 thousand days and nights of data collected by zero-burden technologies, such as under-the-mattress bed sensors, contactless monitoring of bed occupancy and environmental sensors. Researchers found that bedroom temperature and daytime indoor light are associated with objectively measured sleep.
The study found that seasonal changes in the outdoor temperature and light environment were reflected in changes in the indoor environment, with associated changes in sleep timing, duration and heart rate patterns. Even accounting for seasonal changes, on nights that bedrooms were hotter than usual, people living with dementia had more disrupted sleep and higher breathing rates, while on days on which light indoors was brighter than usual, people had longer, less fragmented sleep and lower breathing rates.
Sleep difficulties are commonly reported in dementia, with restless nights, long daytime naps and a disrupted body clock often undermining quality of life, with more memory problems following nights of broken sleep. Improving sleep by optimising bedroom temperature and daytime light may therefore have also beneficial effects on common symptoms in dementia.
Professor Anne Skeldon, Head of the School of Mathematics at the University of Surrey and co-author of the study, said:
"We have analysed millions of hours of data, which has allowed us to see how temperature and light patterns inside the home can impact sleep for people living with dementia. Unlike short-term studies or carer reports, our approach captures long-term patterns in real homes, offering new insights into sleep disruption and how sleep disruption could be reduced."
These zero-burden technologies do not need to be worn or recharged, significantly enhancing their capability to collect data over long periods of time. This enables measurement of sleep characteristics, aspects of breathing and heart rate and indoor light and temperature across seasons and years without any burden to participants.
Working in collaboration with Imperial College London, Surrey and Borders Partnership NHS Foundation Trust, and funded by the UK Dementia Research Institute, through the Care Research & Technology Centre, researchers assessed 26,523 days of data from 70 people living with dementia who were living in their own homes to build a detailed picture of how the environment affects sleep. Data were collected in line with the Care Research & Technology ambition to use zero-burden sensors placed under mattresses and throughout homes, to provide clinical guidance which will help people remain in their own homes for longer.
Surrey's study found that some homes were uniformly hot, day and night, summer and winter. Suggesting that during the winter, turning down the thermostat at night could improve sleep, which may also save on energy costs.
The study also found that the effects of temperature and light varied widely between individuals, suggesting that some people are far more sensitive to seasonal and environmental changes than others. Notably, the team found that sleep timing in people with dementia tended to follow the clock rather than natural sunrise and sunset.
With climate change making hot nights more frequent, ensuring cooler bedrooms and brighter indoor light could become an increasingly important way to improve the daily lives of this vulnerable group, who often spend most of their time indoors.
Professor Derk-Jan Dijk, Director of the Surrey Sleep Research Centre and co-author of the study, said:
"This study demonstrates the power of longitudinal and simultaneous monitoring of the indoor environment, sleep and physiology. We often forget the importance of the indoor environment for health, even though we spend most of our 24-hour day inside. Novel digital health technologies now enable the monitoring of the impact of the indoor environment on physiology and behaviour without any burden to the participants. The further development of 'zero burden technologies' holds great promise for monitoring health and preventing ill-health in the community.'
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