Is it ok to take melatonin every night? i take 5 mg

Melatonin: Melatonin is not known to be harmful. The dose you use is considered safe. However, if there is some reason that you are not sleeping that is important, such as sleep apnea, or poor sleep conditions, melatonin may not be the best solution.

Probably: There are no long-term studies on the use of melatonin and so there are no recommendations for length of use. The supplement is safe and if it helps you sleep well then it is probably OK to take nightly. If it stops working at the 5 mg dose then I would suggest seeing a sleep doctor for further evaluation.