Vaz Fragoso CA, Miller ME, King AC, Kritchevsky SB, Liu CK, Myers VH, Nadkarni NK, Pahor M, Spring BJ, Gill TM. Effect of Structured Physical Activity on Sleep-Wake Behaviors in Sedentary Elderly Adults with Mobility Limitations. J Am Geriatr Soc. 2015 Jul; 63(7):1381-90.