Generally, no. Neither federal nor California law requires a minimum amount of time between shifts, except in certain industries or situations.
Returning to work within the same workday may trigger split-shift or reporting-time pay. A split shift (a schedule interrupted by unpaid, non-meal/rest periods) may require an additional hour of pay at minimum wage, subject to offsets.
Exceptions include:
Overtime depends on how hours fall within the employer’s defined 24-hour workday, not the time between shifts.
A few local jurisdictions have passed ordinances that may require a certain amount of time between shifts, including the Los Angeles City Fair Work Week Ordinance and the Emeryville Fair Workweek Ordinance.
Use the Local Ordinance Wizard to help determine if any apply.