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.
Number of individuals with at least one mobile phone activity (call, sms, likes, status) in four consecutive weeks (dark blue bars) relative to their self-reported sleeping period (light blue bars). Fridays and weekends are excluded.
