Noradrenergic Dysregulation, Sleep and Cognition in Older Adults with Insomnia

The intervention in this study will involve 28 (+4) days of daily exposure to bright light (BL) for two 60-minute sessions (morning and afternoon). For the intervention, we will use Re-Timer® light glasses emitting light with an intensity of 230μW/cm2 (\~500lux) with a green blue 500nm dominant wavelength (between 480-520nm). Light with these characteristics has been shown effective in suppressing melatonin levels supporting their potential to exert effects on other biological non-visual functions associated with exposure to light relevant for this study. Throughout the intervention, participants will keep a diary to monitor daily use of the glasses. Participants will have weekly phone calls with the research team to encourage compliance and monitor potential side effects.

Participants randomized to the control group will wear for two 60-minute sessions (morning and afternoon) customized dim-red light (RL) control Re-Timer® light glasses (wavelength peak at 632nm, light intensity \< 3 lux).