There is no California or federal law expressly modifying a worker's hourly wage based upon the time of day during which the worker is employed. An employee is entitled to $8.00 per hour minimum wage for the first eight hours of employment, $12,00 per hour for the next four hours, and $16.00 per hour for any hours worked in excess of 12, during any 24 hour period.
There are a few exceptions to the above rules, but none of them are based upon working the "graveyard" or any other work shift.
You may have contractual rights, under your union collective bargaining agreement, which grants you pay differentials based upon work shift. But if the union contract doesn't grant you such rights, then you are only entitled to the same pay as anyone who works a day shift.
Note: Persons under 18 years of age (minors) are subject to different wage laws that prohibit working during certain hours for certain ages. But, no such law exists for adult workers.
Hope this helps.
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