This manuscript by Alshehri et al provide novel evidence for the role of the melatonergic system as a potential target in modulating morphine-seeking behavior. The manuscript has an impressive coordination between methodology, results and discussion. The statistical analyses are nice. The English language and grammar is upt to the mark. There are some minor concerns that needs to be addressed.

1. "Opioid addiction is a national health concern due to elevated risks of drug overdose and death". Which nation is author talking about? They need to be more specific and preferably support it with statistical data. Or do you mean to say international concern?

2. "Furthermore, repetitive use of morphine can cause neuroadaptive changes in the brain, leading to seeking behavior upon cessation of use". Does author mean attention seeking behavior?

3. "To our knowledge, few studies have explored the potential use of melatonin to modulate opioid-seeking behavior in rats using conditioned place preference (CPP)". This sentence does fit well as last sentence of introduction. It should be more clear and conclusive. The authors can mention that only few studies have explored.... followed by a sentence mentioning how their work is adding up on those few studies.