References for “Insomnia late in life”
Buysse DJ, ed. Sleep Disorders and Psychiatry. Review of Psychiatry, Vol. 24. American Psychiatric Publications, 2005.
Campbell SS, et al. "Effects of a Nap on Nighttime Sleep and Waking Function in Older Subjects," Journal of the American Geriatric Society (January 2005): Vol. 53, No. 1, pp. 48-53.