Taking melatonin for a short time can help you fall asleep faster and sleep for a longer period, but experts aren't sure if these improvements are actually noticeable or important in everyday life.

Taking melatonin supplements for a short time can help adults with insomnia fall asleep faster and feel like they're sleeping better. This effect is commonly seen at doses between 0.5 and 5 milligrams.

Melatonin helps people fall asleep faster and sleep longer, but the actual improvement is often too small to make a real difference in how they feel and function during the day, leaving doctors unsure if it's truly worth recommending.

Melatonin doesn't seem to work the same way for everyone with insomnia. While some people get a noticeable boost in how long they sleep, most studies show it only helps a small number of patients compared to a placebo.

Taking melatonin doesn't change most sleep measurements for people with Parkinson's disease, but it might help them fall asleep faster and sleep for a longer total time. It doesn't, however, change the deeper stages or structure of their sleep.

Taking melatonin supplements seems to lower fasting blood sugar levels in adults by about 11.6 mg/dL on average. This effect is strongest in people whose blood sugar is already normal or only slightly high, but researchers caution that the current evidence isn't strong enough to rely on melatonin as a main treatment for blood sugar control.