Bright Light Therapy for Treatment of Sleep Problems Following Mild Traumatic Brain Injury

The purpose of the research study is to understand the effectiveness of a six-week course of light exposure on cognitive functioning, mood, activity, and sleep in people that have suffered a head injury leading to a concussion.

Mild traumatic brain injuries (mTBI) or "concussions" are an increasingly prevalent injury in the investigators society. Patients with post-concussion syndrome have been shown to have deficits on tests of short term memory, divided attention, multi-tasking, information processing speed, and reaction time, as well as alteration in mood and emotional functioning. Many patients have other vague complaints including fatigue, dizziness, irritability, sleep disturbances, and chronic headaches. Furthermore, sleep disruption of one of the most common complaints in patients suffering from traumatic brain injuries, with as many as 40 to 65% of patients with mTBI complaining of insomnia. Sleep problems in these patients are associated with poorer outcome, while resolution of the sleep disturbance is associated with improvement in cognitive functioning.

Despite recent evidence of the correlation between sleep quality and recovery from traumatic brain injury, and the well-established role of sleep in neural plasticity and neurogenesis, there have been virtually no direct studies of the causal effects of sleep on recovery following mTBI. However, it is quite likely that sleep plays a critical role in recovery following brain injury.

A particularly promising non-pharmacologic approach that shows potential in improving/modifying abnormalities of the circadian rhythm and sleep-wake schedule is bright light therapy. For the proposed investigation, the investigators hypothesize that bright light therapy may be helpful in improving the sleep of patients with a recent history of mTBI and may also have other mood elevating effects, both of which should promote positive treatment outcome in these individuals. Bright light therapy may increase the likelihood that they will recover more quickly, benefit more extensively from other forms of therapy, and build emotional and cognitive resilience.

This study will also have a healthy control (HC)/effect localization arm that will assist in identifying and mapping the brain systems before and after light exposure so that researchers may develop further insights into the relationship between concussion, light exposure, sleep, and brain function. This healthy control arm will also provide brain targets for study in the analysis of the Main Study Arm.

Eligibility Criteria:
Inclusion criteria:

* Age range between 18 and 50.
* The primary language of the subjects must be English.
* Subjects have experienced a "concussion" or mTBI within the preceding 18 months, but no sooner that 4 weeks prior to their screening. The occurrence of a concussion or mTBI must be documented by a medical report or other professional witness documentation.
* If documented, Glasgow Coma Scale in the range of 13-15 following the injury.
* Subjects must have complaints of sleep difficulties that emerged or worsened following the most recent head injury.
* At least half of subjects must have evidence of sleep onset insomnia or delayed sleep phase disorder.

Exclusion criteria:

* Any other history of neurological illness, current Diagnostic Statistical Manual (DSM-IV) Axis I disorder, lifetime history of psychotic disorder, or head injury with loss of consciousness \> 30 minutes
* Complicating medical conditions that may influence the outcome of neuropsychological assessment or functional imaging (e.g., HIV, brain tumor, etc.)
* Abnormal visual acuity that is not corrected by contact lenses
* Metal within the body, claustrophobia, or other contraindications for neuroimaging
* Less than 9th grade education
* Excess current alcohol use (more than 2 instances of intake of 5+ drinks (men) when or 4+ drinks (women) when drinking in the past two months, and/or on average drinking \> 2 drinks per day (men); \> 1 drinks per day (women) during the past two months
* History of alcoholism or substance use disorder
* Significant use of illicit drugs
* History of marijuana use within the past 6 weeks and/or use of marijuana before the age of 16.

Subjects who engage in shift-work, night work, or who have substantially desynchronized work-sleep schedules (i.e., sleeping later than 10:00 a.m. more than once a week) will be excluded.