Researchers at the University of California studied 42 people with insomnia following mild traumatic brain injury. It was found that 36% had Circadian Rhythm Sleep Disorders (CRSD), the figure a several times higher than found in the general population, 8% had delayed phase sleep syndrome and 7% had irregular sleep-wake patterns. This suggests that mild head injuries were linked with a higher risk of sleep disorders.
Neurology. 2007 Apr.3: 68 (14): 1136-40