Feeling groggy and bleary-eyed at night is a sure sign that melatonin is doing its job. Aptly nicknamed the hormone of darkness, melatonin is a hormone that synchronizes our sleep schedule to the nighttime hours.
Levels of melatonin are highest just before bedtime, according to the Mayo Clinic. As darkness falls, the change in light triggers a chain of events within two key brain structures, ultimately leading to melatonin's release.
First the body's master clock, the suprachiasmatic nucleus (SCN), receives information about the change in light intensity from the eyes. Then, the SCN stimulates the pinecone-shaped pineal gland, which opens the floodgates and releases melatonin to the body. Daylight has the exact opposite effect.
Recent research suggests that melatonin may also play a role in memory. A study in the November 2009 issue of Science showed that zebrafish were better at performing a task when trained during the day than at night. The scientists wrote that sleep is reached when melatonin dims the brain's responsiveness to its surroundings, and because the hormone inhibits the brain at night, it also allows events from earlier in the day to crystallize in the memory.
Not only may melatonin play a role in forming memories, it also might help us live longer, according to research from the February issue of the journal Experimental Biology and Medicine. Melatonin is one of the ingredients in an elixir-of-life serum that was found to put a spring in the step of old mice. The scientists are now working on a longevity supplement for human consumption based on this recipe.
Got a question? Email it to Life's Little Mysteries and we'll try to answer it. Due to the volume of questions, we unfortunately can't reply individually, but we will publish answers to the most intriguing questions, so check back soon.