Related Experiment Video
Updated: Aug 21, 2026

Association Between Sleep Quality and Cognitive Symptoms in Patients with Major Depressive Disorder
Published on: April 26, 2024
The timing of activity rhythms in patients with dementia is related to survival
Phil Gehrman1, Matthew Marler, Jennifer L Martin
1SDSU/UCSD Joint Doctoral Program in Clinical Psychology, Department of Psychiatry, University of California, San Diego, USA.
Background:
Older adults with dementia often have disruptions in circadian rhythms, including disruptions of the rest-activity rhythm. These disruptions are a product of internal neuronal activity and external environmental influences, both of which are deficient in dementia. However, the consequences of disturbed rhythms are unknown. This study examined the relationship between rest-activity rhythms and death in patients with dementia.
Methods:
The authors recruited 149 older adults with dementia (104 women; mean age, 84.1 years) from nursing homes. Activity was recorded with wrist actigraphs from each participant for 3 days. Survival was determined by examining public death records. Cox proportional hazards models were used to determine which aspects of rest-activity rhythms were related to survival.
Results:
The timing of each participant's rest-activity rhythm compared with a sample of persons without dementia was related to survival, such that those who more closely resembled the persons without dementia lived longer.
Conclusions:
Although rest-activity rhythms as a whole were not related to survival, the timing of the rhythm was. Patients with dementia appear to develop an abnormal timing of their rhythms, which is predictive of shorter survival. It may be possible to intervene with these patients to correct the timing of their rhythms and possibly prolong their lives.
Related Concept Videos
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Dysrhythmias VII: Nursing Management of Dysrhythmias
Dementia
The progression of dementia is generally gradual.
Pulse rhythm
Conversely, an irregular pulse pattern is termed dysrhythmia, stemming from disruptions in cardiac muscle...
Dementia l: Introduction