The rhythms of activity across the 24-h sleep-wake cycle, determined in part by the circadian clock, change with aging. Few large-scale studies measured the activity rhythm objectively in the general population. The present population-based study in middle-aged and elderly persons evaluated how activity rhythms change with age, and additionally investigated sociodemographics, mental health, lifestyle, and sleep characteristics as determinants of rhythms of activity. Activity rhythms were measured objectively with actigraphy. Recordings of at least 96 h (138 ± 14 h, mean ± SD) were collected from 1734 people (age: 62 ± 9.4 yrs) participating in the Rotterdam Study. Activity rhythms were quantified by calculating interdaily stability, i.e., the stability of the rhythm over days, and intradaily variability, i.e., the fragmentation of the rhythm relative to its 24-h amplitude. We assessed age, gender, presence of a partner, employment, cognitive functioning, depressive symptoms, body mass index (BMI), coffee use, alcohol use, and smoking as determinants. The results indicate that older age is associated with a more stable 24-h activity profile (β = 0.07, p = 0.02), but also with a more fragmented distribution of periods of activity and inactivity (β = 0.20, p < 0.001). Having more depressive symptoms was related to less stable (β = -0.07, p = 0.005) and more fragmented (β = 0.10, p < 0.001) rhythms. A high BMI and smoking were also associated with less stable rhythms (BMI: β = -0.11, p < 0.001; smoking: β = -0.11, p < 0.001) and more fragmented rhythms (BMI: β = 0.09, p < 0.001; smoking: β = 0.11, p < 0.001). We conclude that with older age the 24-h activity rhythm becomes more rigid, whereas the ability to maintain either an active or inactive state for a longer period of time is compromised. Both characteristics appear to be important for major health issues in old age.

Our study in middle-aged and elderly persons suggests that fragmentation of the 24-hr activity rhythm is associated with depression and anxiety. Moreover, this association also largely accounts for the effect of disturbed sleep on these psychiatric disorders.

Circadian rhythms and sleep patterns change as people age. Little is known about the associations between circadian rhythms and mortality rates. We investigated whether 24-hour activity rhythms and sleep characteristics independently predicted mortality. Actigraphy was used to determine the stability and fragmentation of the 24-hour activity rhythm in 1,734 persons (aged 45-98 years) from the Rotterdam Study (2004-2013). Sleep was assessed objectively using actigraphy and subjectively using sleep diaries to estimate sleep duration, sleep onset latency, and waking after sleep onset. The mean follow-up time was 7.3 years; 154 participants (8.9%) died. Sleep measures were not related to mortality after adjustment for health parameters. In contrast, a more stable 24-hour activity rhythm was associated with a lower mortality risk (per 1 standard deviation, hazard ratio = 0.83, 95% confidence interval: 0.71, 0.96), and a more fragmented rhythm was associated with a higher mortality risk (per 1 standard deviation, hazard ratio = 1.22, 95% confidence interval: 1.04, 1.44). Low stability and high fragmentation of the 24-hour activity rhythm predicted all-cause mortality, whereas estimates from actigraphy and sleep diaries did not. Disturbed circadian activity rhythms reflect age-related alterations in the biological clock and could be an indicator of disease.

Disturbances of sleep and the 24-h activity rhythm were independently related to cognition; while persons with longer sleep-onset latencies had worse performance on memory and verbal tasks, persons with 24-h rhythm disturbances performed less on executive functioning and perceptual speed tasks.

Emotion regulation refers to strategies through which individuals influence their experience and expression of emotions. Two typical strategies are reappraisal, a cognitive strategy for reframing the context of an emotional experience, and suppression, a behavioral strategy for inhibiting emotional responses. Functional neuroimaging studies have revealed that regions of the prefrontal cortex modulate amygdala reactivity during both strategies, but relatively greater down-regulation of the amygdala occurs during reappraisal. Moreover, these studies demonstrated that engagement of this modulatory circuitry varies as a function of gender. The uncinate fasciculus is a major structural pathway connecting regions of the anterior temporal lobe, including the amygdala, to inferior frontal regions, especially the orbitofrontal cortex. The objective of the current study was to map variability in the structural integrity of the uncinate fasciculus onto individual differences in self-reported typical use of reappraisal and suppression. Diffusion tensor imaging was used in 194 young adults to derive regional fractional anisotropy values for the right and left uncinate fasciculus. All participants also completed the Emotion Regulation Questionnaire. In women but not men, self-reported typical reappraisal use was positively correlated with fractional anisotropy values in a region of the left uncinate fasciculus within the orbitofrontal cortex. In contrast, typical use of suppression was not significantly correlated with fractional anisotropy in any region of the uncinate fasciculus in either men or women. Our data suggest that in women typical reappraisal use is specifically related to the integrity of white matter pathways linking the amygdala and prefrontal cortex.