To characterize changes in nighttime cyclic variation in HR (CVHR) with advancing age in older adults, CVHR was quantified for N=56 adults with 2 Holter recordings 5 yrs apart (CHS1 and CHS 2) in the Cardiovascular Health Study (CHS) and 2 overnight polysomnograms 5 yrs apart in the Sleep Heart Health Study (SHHS1 and SHHS2) using MatLab. Baseline age was 71±3yrs. The number of CVHR events was also normalized to time in bed (CVHR Index). CVHR Index did not change across recordings, but males had higher values (p=0.009). Mean HR increase during CVHR was similar in the first 3 recording but declined on the last (p<0.02). CVHR duration increased, but CHS1 vs. CHS2 and SHHS1 vs. SHHS2 were NS (rest, p<0.007). We conclude that CVHR is frequent at night in older adults, but results suggest an age-related trend towards decreased magnitude and longer durations of HR arousals, possibly due to the aging of the autonomic nervous system.