Sleep problems associated with aging may be caused by changes in hormone balance, according to a new study in Switzerland (Pagani L et al. Proc Natl Acad Sci U S A. 2011;108:7218-7223). Human sleep-wake cycles drift earlier and earlier as individuals age, which can lead to interrupted and less restful sleep and more frequent daytime napping.
The investigators found that when skin fibroblasts from 18 young and 18 elderly individuals were grown in bovine serum, they had the same internal circadian cycles, but when the cells were grown in human sera from older individuals, their biological clocks shifted to reflect the disrupted sleep patterns of the elderly.
Hampton T. Sleep and the Elderly. JAMA. 2011;305(21):2162. doi:10.1001/jama.2011.723