Could bright light directed at comatose patients affect their natural circadian rhythms and help them wake up from coma? A small study from Austria suggests that this is possible.
New research
A person's ability to recover from a coma after suffering a severe traumatic brain injury has been linked to maintaining natural circadian rhythms, according to a study in 18 unconscious patients.
Scientists have found that there is a better chance of recovering consciousness if the body is returned to its natural, healthy temperature cycle throughout the day.
In addition, the scientists found that, of a subgroup of eight patients, two showed signs of consciousness after being exposed to bright light, which was designed to activate the circadian rhythm and natural daily changes in body temperature.
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"The closer a person's body temperature is to normal after a brain injury, the more likely they are to regain consciousness after a coma," said study leader Christine Blum, at the Sleep and Consciousness Laboratory at the University of Salzburg in Austria.
The new results are preliminary, but scientists believe that controlling circadian rhythms can be used as a diagnostic tool to improve the comatose patient's chances of recovery. In addition, treatments aimed at fine-tuning these rhythms can help patients become more conscious, the research team points out in a report published April 19 in the journal Neurology.
What are circadian rhythms
These are the daily cycles that tell the person's body when to eat, sleep, or wake up. They are set by environmental signals such as daylight and darkness. In healthy people, these rhythms involve small changes in body temperature. Typically, it rises during the day and peaks around 4:00 pm and then decreases during the night. The maximum decrease in body temperature is observed at 4 am.
What can be the condition of comatose patients
As part of the new study, scientists monitored the condition of 18 people with severe head injuries. Some of them were diagnosed with a so-called vegetative state. People in this state wake up from a coma (which is a state of complete unconsciousness), can open their eyes and have periods of sleep, but remain indifferent to everything that is happening around. Other patients in the study were minimally conscious, that is, they showed some signs of consciousness.
Scientists work
Throughout the week, scientists continuously monitored the participants' body temperatures using external sensors on their skin. They also assessed the level of consciousness of each person using a specially designed scale, measuring indicators such as reaction to sound and the ability to open the eyes with or without stimulation. The researchers found that patients who scored higher on this scale also had a body temperature close to that of a healthy 24-hour rhythm.
The researchers then tried to return eight patients to a more natural temperature cycle. They used bright light stimulation for them at cyclic periods throughout the week. Two participants responded positively to this therapy, expressing signs of consciousness.
Disadvantages of research
Blum warned, however, that her team only studied eight patients, a sample too small to argue that light stimulation is a useful therapeutic tool that can help brain injury patients regain awareness. “This method is promising, but it is too early to draw conclusions, as these results should be tested in advance in a larger group,” she said.
“We really hope we can work on the cycle to help patients wake up from coma,” Bloom added. “Therefore, we urge doctors to create an environment in the hospital that mimics the natural cycle of light during the day and darkness at night. Fluorescent lamps can be especially useful.
Anna Pismenna