Cancer stems from a host of things, not just one thing like working at night. Disease results from negative thoughts/mindset, negative attitude, poor diet; insalubrious lifestyle, and insalubrious environment. You don't need to take melatonin. Your body (pineal gland) produces it. As a night worker, just make sure when you are sleeping in the day time your room is completely dark, just like how Dracula used to sleep in the darkness of his coffin during the daylight hours. This is why Dracula was a thousand years old but looked young. He slept during the day (which produces melatonin which is an anti-aging hormone) and he operated at night whereby he also produced melatonin. Dude never aged! You do the same, just don't suck on no necks to get blood though -- LOL!!!! And no! There are no herbs to reverse anything that comes from actions or behaviors that are unnatural. You reverse the effects of night-time work by doing the opposite. In your case, it's your job (which you don't want to quit unless you can find another one), so you just get some good sleep during the day in pitch darkness.