Question: Hi there,

I had some questions about living a nocturnal schedule. I'm a 35 year old male who, for the last 12 years or so, has (by choice and working for myself) lived mostly a nocturnal schedule. That is to say I usually wake up at 3 or 4 in the afternoon and go to bed at 7 or 8 in the morning. I tend to sleep fairly well most nights (I aim for 6-7 hours a night; occasionally I get 8+). While I am obese, I do exercise regularly, walk lots, and try to eat healthy. I don't smoke, but I do drink (I try to keep it decently moderate since my 20's). I also take several supplements (multivitamin, fish oil, Q10, garlic, fruits/veggie powder as well as the real things, etc.).

Several studies have seemed to indicate people who go against their circadian rhythms have ~3X the cancer risk, more cardiovascular risk, higher chance of metabolic problems, etc. This has worried me, and I want to see what I can do to reduce or eliminate the risk. I should say a lot of these studies, but not all (some show increased risk even with a fixed schedule), deal with rotating schedules (ie. night shift two weeks, day shift the next two weeks), which ISN'T a regular problem for me - my schedule stays fairly consistent (a few exceptions within a year, but not that many).

Additionally, last year when I visited my doctor, I checked Vitamin D levels and have increased Vitamin D along with her recommendation (in addition to getting some sunshine in the afternoon hours). I do sleep with the blinds closed, but it's not a completely dark room. That doesn't seem to bother me, though. I've considered taking low dose melatonin nightly, but have yet to discuss it with my doctor.

I could potentially shift to a day schedule, but I really don't want to if I can avoid it and still be healthy maintaining my nights schedule.

My questions:
1.) I've always kind of gravitated toward this schedule. Is it possible for this to be someone's "natural" rhythm?
2.) Is there any reason, aside from Vitamin D and melatonin, that people who are awake at night are prone to all these risks, or can supplementation of D and melatonin potentially even things out with the general population?
3.) Is it okay for my room to NOT be pitch black when I sleep?
4.) Is a fixed nights schedule any better than someone who's constantly rotating?
5.) Any other suggestions to minimize risk?
6.) In your opinion, if I'm happier like this at night, should I still consider moving to a day schedule for health reasons alone?

Thank you for your time.

Thanks very much!

I appreciate that the fact that having a fixed schedule and not being deprived of sleep, in addition to a reasonably healthy lifestyle overall, are in my favor as far as potential risks of night work.

I also understand that Vitamin D supplementation, as well as sun exposure when I can, work in my favor.

Regarding the melatonin, I was considering a small dose (1-3 mg) before bed, but will be sure to talk to my nutritionist and personal physician about that - of course I can't get sleepy during the day, but it appears to have anti-cancer benefits, so I do want to make sure my levels are normal. Is that something that can be tested by my doctor?

Thanks for all your help and reassurances!

Last question. Is the increased cancer risk in shift workers most likely (I'd say definitely, but I know there are no 100%'s in medicine) due to melatonin (or possibly Vitamin D) deficiencies? Or are there other possibilities (aside from not getting enough sleep/rotating shifts) not accounted for? Thanks again - this has been most helpful!