Samantha Hopkins, Peter Lloyd Morgan, Luc J.M. Schlangen , Peter Williams, Debra J. Skene and Benita Middleton* Pages 1053 - 1062 ( 10 )
Objective: Environmental (little outdoor light; low indoor lighting) and age-related physiological factors (reduced light transmission through the ocular lens, reduced mobility) contribute to a light-deprived environment for older people living in care homes.Methods: This study investigates the effect of increasing indoor light levels with blue-enriched white lighting on objective (rest-activity rhythms, performance) and self-reported (mood, sleep, alertness) measures in older people. Eighty residents (69 female), aged 86 ± 8 yrs (mean ± SD), participated (MMSE 19 ± 6). Overhead fluorescent lighting was installed in communal rooms (n=20) of seven care homes. Four weeks of blue-enriched white lighting (17000 K ≅ 900 lux) were compared with four weeks of control white lighting (4000 K ≅ 200 lux), separated by three weeks wash-out. Participants completed validated mood and sleep questionnaires, psychomotor vigilance task (PVT) and wore activity and light monitors (AWL). Rest-activity rhythms were assessed by cosinor, non-parametric circadian rhythm (NPCRA) and actigraphic sleep analysis. Blue-enriched (17000 K) light increased wake time and activity during sleep decreasing actual sleep time, sleep percentage and sleep efficiency (p < 0.05) (actigraphic sleep). Compared to 4000 K lighting, blue-enriched 17000 K lighting significantly (p < 0.05) advanced the timing of participants’ rest-activity rhythm (cosinor), increased daytime and night-time activity (NPCRA), reduced subjective anxiety (HADA) and sleep quality (PSQI). There was no difference between the two light conditions in daytime alertness and performance (PVT). Conclusion: Blue-enriched lighting produced some positive (increased daytime activity, reduced anxiety) and negative (increased night-time activity, reduced sleep efficiency and quality) effects in older people.
Care home, light therapy, mood, elderly, rest-activity, sleep.
Centre for Chronobiology, Faculty of Health & Medical Sciences, University of Surrey, Guilford, Surrey, Centre for Chronobiology, Faculty of Health & Medical Sciences, University of Surrey, Guilford, Surrey, Philips Research, Eindhoven, Dept. of Mathematics, Faculty of Engineering & Physical Sciences, University of Surrey, Centre for Chronobiology, Faculty of Health & Medical Sciences, University of Surrey, Guilford, Surrey, Centre for Chronobiology, Faculty of Health & Medical Science, University of Surrey, Guildford, Surrey, GU2 7XH