Your melatonin levels can be tested with a blood test, urine test or saliva test. If you are concerned that you may actually be melatonin deficient, ask your doctor about testing. Melatonin is produced by the pineal gland and sends a signal to regulate the sleep-wake cycle in the sleep center of the brain. Interestingly, melatonin is also produced in the retina, the skin, and the GI tract, but this is not the melatonin what affects your biological sleep clock melatonin pills.
This is the really important thing you should understand about melatonin: melatonin is a sleep and body clock regulator NOT a sleep initiator. Melatonin works with your biological clock by telling your brain when it is time to sleep. Melatonin does not increase your sleep drive or need for sleep.
Melatonin is called the “Vampire Hormone” because it is produced primarily in darkness and inhibited by light. The levels of your melatonin increase in the middle of the night and gradually fall as the night turns to morning, so exposure to light before bed can push your biological clock in the wrong direction – making melatonin ineffective.