My son has issues managing time zones. His health is affected. He has become more irritable than before. What should I suggest to him?

Why does your son have to "manage time zones"????  Do you frequently travel from one zone to another?

I do not know what time zones have to do with it.  My son goes to sleep when it’s dark and wakes up when it’s bright.  When i came back from the Philippines (13 hours ahead) where i live.  It only took me a couple days to get back to normal.  Basically forcing myself to stay awake when i was incredibly tired to fall asleep when everyone else was

I would suggest that you have a word with him and ask what is happening in his life. Tell him about the issues that you observe he is facing and talk to him about seeking professional help for the same. Choose the right time to talk. If you can solve it on a personal level well and good else counselling becomes the only choice. Read ‘Stress diaries’ a book written by Dr. Rachna Khanna Singh and I’m sure it’ll help you the way it helped me.