RT Journal A1 Hampton T T1 SLeep and the elderly JF JAMA JO JAMA YR 2011 FD June 1 VO 305 IS 21 SP 2162 OP 2162 DO 10.1001/jama.2011.723 UL http://dx.doi.org/10.1001/jama.2011.723 AB 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.