Healthy elderly women and men have different entrained circadian temperature rhythms.

Body core temperature was measured in healthy elderly men and women under entrained conditions. Female subjects showed a larger amplitude and a higher peak temperature than male subjects. In addition, acrophase was advanced for females by an average of 49 minutes. Variability in acrophase was greater for males than females. This pattern of gender differences varies considerably from the pattern others have observed in young subjects, suggesting that aging may affect the circadian timing system of males and females differently.