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.