Can I take melatonin and ambien (zolpidem) (10mg) together? Ambien (zolpidem) has lost it's effects and melatonin barely works. Whats an overdose level?

Melatonin and Ambien (zolpidem) do not have significant interaction. Melatonin (OTC) has a role in regulation of the sleep-wake cycle. May dose up to 20 mg/d. Ambien (zolpidem) (prescribed) improves sleep onset; best taken without food. If effect lost then consult prescriber to review your situation and determine best course of action. Review good sleep hygiene (https://sleepfoundation.org/ask-the-expert/sleep-hygiene). Best regards.