Under California's Wage Orders -
“Split shift” means a work schedule, which is interrupted by non-paid non-working periods established by the employer, other than bona fide rest or meal periods.
And "when an employee works a split shift, one (1) hour’s pay at the minimum wage shall be paid in addition to the minimum wage for that workday, except when the employee resides at the place of employment."
The question is: If you work an over night shift, such that you start at 10:p.m., end your shift at 7:00 a.m., and then return to work later the same day, is that a split shift? No, said the Court of Appeal in Securitas Security Services, Inc. v. Superior Court (opinion here).
So, DLSE? You don't have to issue that opinion letter I asked you to issue years ago. (!)
DGV