Internal Time: The Science of Chronotypes:

*Internal Time: The Science of Chronotypes, Social Jet Lag, and Why You’re
So Tired*

The disconnect between our internal, biological time and social time —
defined by our work schedules and social engagements — leads to what
Roenneberg calls *social jet lag*, a kind of chronic exhaustion resembling
the symptoms of jet lag and comparable to having to work for a company a
few time zones to the east of your home.