Bright light therapy lamps can improve sleep, activity levels and circadian rhythms of older adults in urban areas who have diminished exposure to natural light, a new study from the University of Surrey reports. Scientists believe such methods could provide a non-pharmacological and low-cost way to support healthy ageing in urban areas.
In the first real-world study of its kind, Surrey scientists, as part of the European-wide ENLIGHTENme project, investigated whether the benefits of light supplementation from bright light therapy lamps could be translated into everyday life. Controlled studies under laboratory conditions have consistently shown that similar lamps can reduce circadian misalignment, which, when left unaddressed, can lead to sleep problems, hormone imbalances and increased risks of metabolic and cardiovascular diseases. Recognising that real-world light exposure is heavily shaped by behavioural and environmental factors, the team also examined the key determinants influencing how and when people actually use these lamps.
Dr Daan van Der Veen, Senior Lecturer in Sleep and Chronobiology at the University of Surrey, said:
"Exposure to daytime light is crucial to regulate our circadian rhythms and our sleeping patterns, however often older adults in urban areas, due to the decline in their eyesight or perhaps mobility issues preventing them from going outside, do not get this exposure to good light, and this can lead to sleep and health problems, increasing their risk to chronic diseases."
During the study scientists recruited more than 200 participants aged 63 -92 years old from three culturally diverse European cities (Tartu, Bologna and Amsterdam) whose seasonal daylight variation differed from each other.
Professor Debra Skene, Professor of Neuroendocrinology at the University of Surrey said:
"We are very excited that the findings we have shown in laboratory studies of older people are now replicated in real-life conditions, with varying levels of natural light and in different cultures."
Following two weeks of baseline assessments, participants were split into two groups – a light supplementation group, who were provided with a light therapy lamp and a control group who did not have a lamp. Those in the light supplementation group were asked to place the lamp at head height in the room where they spend most of their time whilst at home and were instructed to turn on the lamp within one hour after waking up and turn it off four hours before their normal sleep time at the latest for a period of 12 weeks.
All participants wore a wrist actigraphy monitor and a pendant light sensor to measure activity levels and exposure to light. The study was repeated across all seasons to account for changes in natural light.
Scientists found that participants with higher baseline natural light exposure showed significantly higher daytime levels of activity, more consolidated wakefulness during the day, and reported better sleep quality compared to those with lower light exposure.
It was also found that those classified as 'morning types, or larks' and began light supplementation earlier in the morning were significantly more active during the day and had less disrupted rest-activity rhythms than their peers who started later in the morning. In addition, the group which finished light supplementation earlier, thereby reducing evening light exposure, showed lower rest-activity fragmentation.
Analysis of the data provided by participants during initial baseline assessments showed that participants with metabolic disorders (including high blood pressure, diabetes, obesity, cardiovascular conditions) had significantly lower levels of total light exposure compared to those who did not report a metabolic disorder.
Débora Constantino, a Postgraduate Research Student at the University of Surrey, said:
"What we have found is that early administration of light supplementation significantly enhances activity levels and reduces rest-activity fragmentation in older adults.
"This is an exciting discovery and provides real-world evidence that light is a simple, non-pharmacological, and potentially cost-effective intervention, which, from a public health policy perspective, could help support healthy ageing. These findings highlight a clear opportunity for policymakers to integrate structured indoor light supplementation into community care frameworks and care home guidelines."
This study was published in the Journal of Pineal Research (paper available on request))
