Night shifts for six years. My body clock has left the chat. Any real tips?

Hospital pharmacy, 8 pm to 8 am, four nights a week. I have done it since 2020. I sleep from 9 am to about 2 pm, then the twins wake up and that is the end of it. Symptoms: constant mild headache, I have gained 9 kg, I am irritable with everyone, and my last blood test showed vitamin D almost zero, which is funny because I never see the sun. I cannot change the job right now. What I can change is what I do around it. People who have survived long term night work, what actually helped? Blackout curtains, timing of meals, when to drink chai, anything that is not "just switch to days".