What health issues can cause dry eyes?

If I goto bed at 3 or 4 am every night would that be a reason why my eyes are always in pain and dry?
I usually get 8 hrs of sleep but I never get to bed early, so I am starting to think sleeping at late hrs could be a reason for this.

It is very possible that your eyes drift open just a tiny bit while you are sleeping and the cornea dries out. That hurts like hell. Bausch & Lomb makes a product called moisture eyes pm ... It is in a very small tube, and not cheap, but works wonders. It is an ointment with the consistency of vaseline. Hold the lower lid of your eye down and put a tiny bit in your eyes just before you fall asleep. My problem is a little more complicated, so I have to tape my eyes closed if I use a ceiling fan. Next time you go to the eye doctor, tell him your experiences. He may want to check your tear ducts.

No way that sleep or lack of sleep is causing it, though sleep issues can contribute to the problem. What might be causing it is that while you sleep you don't close your eyes all the way. I have had a terrible time with dry eyes. It feels like an ice pick is going though the eye. It was Lasik that caused my problem. I have had to have punctal plugs inserted into the bottom lids of both my eyes (lower tear ducts closed) and I had the upper right eye tear duct cauterized shut. My right eye has no tear ducts anymore and I still can have problems. I use "Tears Naturale" a lot and I use a gel tear substitute at night and that really helps. I also use a mask over my eyes to help my eyes stay closed. Turning off the overhead fan, if you use one, helps. The Dr. thinks I have Sjogrens Syndrome because I also lose moisture in my mouth (and that is very scary. you can't swallow without spit!!)
There are other health issues that can cause dry eyes, from anxiety, menopause, to other syndromes and diseases!! Even the weather can affect the moisture in your eyes. Medications can too. Some are very drying!