People who have suffered traumatic brain injuries may experience difficulty sleeping due to a reduced capacity to produce the hormone melatonin, according to the results of a new Australian study. Looking at the sleep patterns of twenty-three brain trauma patients and twenty-three healthy participants, researchers found brain injury sufferers produced lower melatonin in the crucial hours leading up to sleep, stayed awake longer and had a lower likelihood of achieving sustained REM sleep compared to healthy people.

The reduced ability to sleep is well-known in brain injury sufferers with conditions such as insomnia and depression being commonly experienced, but the reasons for this were up until now unknown. The results of the study – published in the American Academy of Neurology journal – could lead to improved treatment for sufferers.

“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,” said Shantha Rajaratnam PhD from Monash University in Victoria, Australia. “These results suggest that the brain injury may disrupt the brain structures that regulate sleep, including production of melatonin.”