We found that light exposure and time outdoors influenced morning melatonin concentration. No differences in melatonin or the ipRGC-driven pupil response were observed between refractive error groups, although myopes exhibited poor sleep quality compared to emmetropes. Findings suggest that a complex relationship between light exposure, ipRGCs, refractive error, and sleep exists.

The use of short wavelength-blocking glasses at night increased subjectively measured sleep quality and objectively measured melatonin levels and sleep duration, presumably as a result of decreased night-time stimulation of ipRGCs. Alterations in the ipRGC-driven pupil response suggest a shift in circadian phase. Results suggest that minimising short wavelength light following sunset may help in regulating sleep patterns.