This is what poison control says. According to them you should have someone waken you every 30 minutes until you are awake. There's more specifics in the article. It's unlikely to do great damage but it's also way more than you are supposed to take so caution is needed. The other articles mention your blood pressure could be low so watch for dizziness:
Potential Uses and Benefits of Melatonin | Poison Control

These are a few more articles about melatonin.



Can You Overdose on Melatonin? How to Determine the Right Dosage

Can You Overdose on Melatonin? - PCSI