I have had chronic insomnia for years and in order not to use prescription sleep meds, I relied on melatonin, thinking it was good for glaucoma folks. I noticed that my sleep was still not great and I felt even worse the next day, including an increase in my dry eyes. I have since stopped taking any melatonin, and think that my circadian rhythm has been totally altered, at least for now. When I spend time out in the sun, I find it almost impossible to sleep at night. I know that this is counter to what all the documentation says and if one more doctor tells me that this is a paradoxical response, I think I am going to scream. I have tried the yellow glasses a few hours before bedtime to see if that helps, but it only makes it worse. I am wondering if anyone has encountered this? I am hopeful that in time, my natural body clock will kick in and I will be able to once again enjoy walking outside without worrying about it impacting negatively on my sleep.
I have heard of something similar in police officers. I was told by a police officer that heavy use of melatonin was a common practice in their department, and that some officers who took high doses of melatonin (e.g., 10 mg) experienced this paradoxical effect. The answer, in their case, was to use a much lower dose. Even a fraction of a milligram (say 300 mcg or 600 mcg) could be sufficient for many people to experience the benefits of melatonin.
Personally, melatonin helped me improve my sleep and sleep schedule. Sorry I cannot offer a definitive answer.