Systematic Light Exposure in Pediatric Brain Tumor Survivors

Participants will be randomized to take part in one of two groups: 1. The Bright Light Group will be exposed to bright light (1,000 lux at eye level) using light glasses (Luminette Version 3) for a maximum duration of 30 minutes each day from Monday to Friday for a total of 6 weeks. Duration of light exposure will be gradually increased over the first few days until the target of 30 minutes is reached on Day 5. Light duration is for 10 mins on Days 1 \& 2, 20 mins on Days 3 \& 4, and finally, 30 mins on Day 5. 2. The Dim Light Group will be exposed to dim light (equivalent intensity of \<25 lux) for a maximum duration of 30 minutes. Dim light will be given in the same manner and frequency as described for the Bright Light group. Participants will undergo the same evaluations and monitoring throughout the intervention and post-intervention follow-up. All participants will receive a pair of light glasses, with a phone app to track usage, and be fitted with an actigraph following consent to participate. Assessments will be completed at baseline (prior to intervention), with additional assessments at Week 4 (of intervention), Week 6 (end of intervention), and 2-weeks post-intervention (Week 8). Participants and their caregivers will complete questionnaires assessing fatigue, sleep, and mood. Psychological testing to measure attention, working memory, executive control, and processing speed will be completed using a computerized, online battery at each time point and in person at baseline and end of intervention. Caregivers will also be asked to complete a questionnaire about the family's general characteristics and medical history. At baseline and end of intervention (Week 6), saliva will be collected. For each day of the intervention, participants will share their usage data and complete a daily sleep diary that includes time spent in bed, sleep/wake times, estimated amount of natural sunlight exposure, and medication use. A research coordinator will contact families on Days 2 and 5 and weekly thereafter for the duration of the intervention to identify possible light-related side effects and to check on compliance with light exposure (both frequency and duration). A remote app will be installed on the participant's or caregiver's cell phone to share light usage, which is tracked automatically once the device is turned on. At end of intervention (Week 6), participants and their caregivers will be asked to complete a short acceptability questionnaire.