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.
Mean of sleep time before and during COVID-19. Urban: includes a capital and metropolis city in South Korea, Suburban: includes a nearby city that surrounds the capital city, Rural: includes the rest of the cities except urban and suburban.
