Overall, melatonin use should not cause delayed drowsiness. If you use an extended-release form of melatonin or you take melatonin without allowing 8 hours of sleep, you may experience drowsiness in the morning. The use of a shorter-acting form of melatonin, like a fast-acting form, should not lead to drowsiness in the morning.Overall, melatonin use should not cause delayed drowsiness. If you use an extended-release form of melatonin or you take melatonin without allowing 8 hours of sleep, you may experience drowsiness in the morning. The use of a shorter-acting form of melatonin, like a fast-acting form, should not lead to drowsiness in the morning.