To the Editor.
—Dr King and colleagues1 reported that, following 16 weeks of exercise training, older adults with moderate sleep complaints exhibited self-reported reductions in sleep-onset latency and increases in sleep duration of approximately 15 minutes and 50 minutes per night, respectively. In an Editorial accompanying the article, Dr Buchner2 stated, "The study found exercise caused improvements in sleep quality." This statement is not defensible scientifically because all plausible alternative explanations for these findings were not ruled out.The circadian system is a major determinant of both sleeponset latency and sleep duration. In older adults, an advanced circadian phase and a reduced circadian amplitude are thought to contribute to sleep disturbances.3 Moreover, the weight of the available evidence suggests that exposure to bright light can be helpful in treating certain sleep problems in the elderly, presumably via a circadian mechanism because appropriately timed exposure to bright light
O'Connor PJ, Youngstedt SD. Sleep Quality in Older Adults: Effects of Exercise Training and Influence of Sunlight Exposure. JAMA. 1997;277(13):1034. doi:10.1001/jama.1997.03540370024017