Australian researchers performed sleep research experiments using 23 patients who had suffered traumatic brain injury an average of 14 months earlier, and a control group of 23 healthy people who spent two nights in a sleep laboratory.
They found that:
- Healthy people produce more melatonin than do people with brain injuries during evening hours, when the chemical is supposed to rise to trigger sleep.
- Patients with brain injury spent less time in bed actually sleeping; that is, they had less “sleep efficiency.”
- Brain injury patients spent more time awake after first falling asleep.
- Brain-injured people spent more time in non-REM sleep.
- Patients with brain injuries had more symptoms of anxiety and depression.
“We’ve known that people often have problems with sleep after brain injury, but we haven’t known much about the exact causes of these problems,” says researcher Shantha Rajaratnam, PhD, of Monash University in Victoria, Australia. “These results suggest that the brain injury may disrupt the brain structures that regulate sleep, including production of melatonin.”
Melatonin, Sleep, and Brain Injuries
Melatonin is a hormone that has been associated with the body’s circadian rhythm and the regulation of diverse body functions. Normally, melatonin levels in the blood are highest just prior to bedtime, signaling sleep. The hormone regulates biological rhythms.
Rajaratnam says future research should look into whether taking melatonin supplements could improve sleep in people with brain injuries.
The study says that:
- Brain injury patients spent an average of 62 minutes per night awake, after initially falling asleep, compared to 27 minutes for the participants in the healthy group.
- Elevated depression is associated with reduced ability to sleep soundly.
- Cerebral damage associated with traumatic brain injury may disrupt the neural structures that regulate sleep, including synthesis of melatonin by the pineal gland.
Study authors write that sleep problems are common in people with traumatic brain injury, with patients complaining of insomnia, hypersomnolence, and altered sleep-wake cycles.
The study is published in Neurology, the medical journal of the American Academy of Neurology.