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The body’s circadian rhythm may play a crucial role in the recovery of consciousness in patients with severe brain injuries, according to a new study by researchers at the University of Surrey in England and the University of Salzburg in Austria.

Our circadian rhythm is an approximate 24-hour cycle regulated by the body’s internal clock that determines several physiological processes in the body, including our core body temperature, which tends to fluctuate throughout the day.

“Prior to our study little was known about the circadian rhythms of patients with brain injuries,” said co-researcher Dr. Nayantara Santhi from the Surrey Sleep Research Centre at the University of Surrey.

“What we have learnt is that the circadian body temperature holds vital clues to the state of consciousness of patients which could potentially enable doctors to tailor medical treatment more effectively. Circadian rhythms hold the secret to the workings of the body and we will be looking further into this in future research.”

For the study, the researchers examined circadian body temperature variations in 18 patients with severe brain injuries. They used four external skin sensors to monitor the circadian rhythm, which was found to range between 23.5 hours and 26.3 hours.

The level of consciousness of each patient was evaluated through the Coma Recovery Scale-Revised, which measures responsiveness to sound or a patient’s ability to spontaneously open eyes without or only with stimulation by the examiner.

The study shows that patients who scored better on the Coma Recovery Scale-Revised, especially those with a stronger arousal, had body temperature patterns more closely aligned with a healthy 24-hour rhythm.

The results demonstrate a relationship between circadian body temperature variation and the level of consciousness of a patient with severe brain damage. This new finding suggests that a patient’s consciousness levels should be assessed during time windows when their circadian rhythm predicts they will be more responsive.

The researchers also investigated the effects of bright light stimulation on patients with severe brain injuries. To measure its effectiveness, eight patients received bright light stimulation, three times per day for one hour over the course of one week.

After one week, improvements were found in the levels of consciousness of two patients, whose conditions improved from vegetative state/unresponsive wakefulness to a minimally conscious state. A shift in circadian body temperature, closer to a healthy 24-hour rhythm was also recorded in both patients.

“Our study suggests that the closer the body temperature patterns of a severely brain injured person are to those of a healthy person’s circadian rhythm, the better they scored on tests of recovery from coma, especially when looking at arousal, which is necessary for consciousness,” said lead author Dr. Christine Blume from the University of Salzburg.

“Circadian variations is something doctors should keep in mind when diagnosing patients, especially the time of the day when patients are tested could be crucial. Also, it may be important to create an environment that mimics the normal light-dark cycle to support a healthy circadian rhythm.”

The study is published in the journal Neurology.

Source: University of Surrey