Related Experiment Video
Updated: May 25, 2026

Recording and Analysis of Circadian Rhythms in Running-wheel Activity in Rodents
Published on: January 24, 2013
Characteristics of infradian and circadian rhythms in the persistent vegetative state
1Department of Neurosurgery, West China Hospital, Sichuan University, Chengdu, China.
Abstract:
This retrospective study investigated the circadian and infradian characteristics of blood pressure and heart rate in 26 patients with traumatic head injury in a persistent vegetative state (PVS). Systolic and diastolic blood pressures and heart rate were measured every hour for the first 240 h (10 days) following hospital admission. These data were analysed for the presence of circadian and infradian rhythms using the least-squares fit of the cosine function with the single cosinor method. Infradian rhythms were defined as biological rhythms with a period of approximately 7 days (circaseptan rhythms). All the patients studied had circadian and circaseptan rhythms of systolic and diastolic blood pressures and heart rate. The amplitudes of all the circaseptan rhythms were significantly greater than those of the corresponding circadian rhythms. It was concluded that there was an altered association between circadian and infradian blood pressure and heart rate rhythms in patients in a PVS. Circadian and infradian rhythms were present, but the infradian rhythm had a greater amplitude than the circadian rhythm.
Related Concept Videos
Biological Clocks and Seasonal Responses
Circadian Rhythms and Gene Regulation
Sleep-Wake Cycles
NREM Sleep
NREM sleep comprises four progressive stages that seamlessly merge:
Stages of Sleep
Before sleep begins, in wakefulness, the brain exhibits primarily beta waves, which are high in frequency and low in amplitude, indicating alertness...