Hi, welcome to the forum, first thing to rule out is hypersomnia. It may present as excessive daytime sleepiness or nocturnal sleep of long duration (as much as 12 h or more) or sleep drunkenness. Your symptoms are due to Shift work.
The sleep problems can be resolved by transferring from the night shift or by adopting a daily sleep routine that is consistent seven days per week. Chronic insomnia may develop in individuals who work the night shift on either a rotating or permanent basis.
The causes can be genetic, medical disorders such as clinical depression, uremia and fibromyalgia. Sometimes hypersomnia may be due to other sleep disorders such as narcolepsy, sleep apnea, and restless leg syndrome.
You can try melatonin against prescription which helps your sleep cycle to bring it to normal.You should consult a sleep specialist for a complete medical and psychological workup.
Take care and regards.
Do you have sleep apnea? If you do you may not realize it.