How much melatonin is okay for a 175lb adult? is it habit forming, or safe?

Melatonin is safe: There is no known toxicity. However, if 3 0r 6 mg of melatonin is ineffective for sleep, then 30 mg will be also. I have used as much as 30 mg daily in patients with brain cancer, but generally 0.5 mg to 3 mg is enough for sleep. Ask your doctor or herbalist for more help if that dose is not useful.

Melatonin: Concur w previous answer. It is usually safe & effective. I often need to use off label dosing with patients (higher than recommended). As w any substance, there are potential side effects to include: feeling tired the next day, sleep walking, nightmares, vivid dreams, dizziness, confusion, headache, GI upset, v libido, v sperm count, gynecomastia in men & mood changes.