Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Light exposure conditions: subjects were exposed either to 6.5 hours of continuous bright light (BL; ~9,500 lux), intermittent bright light [IBL; six 15-minute bright light (~9,500 lux) pulses separated by 60 minutes of very dim light (<1 lux)] or very dim light (VDL; <1 lux).
