Hello sir. Dr Arpit here. There can be a lot of reasons for sleep issues. All the medicines he is taking also need to be known as some medicines can cause lack of sleep.
No, melatonin is taken for excessive sleepiness, since you only wrote " sleep issues " I am presuming it is lack of sleep. These medicines should be taken only on due prescription. So it's a big NO.
Regards
Next Steps
Please consult a neurologist
Health Tips
Please don't give any medication without prescription