This is your Brain on Melatonin

“Your brain’s in a fog. You’re staring at the computer screen, trying to remember something—but you can’t even remember why you’re trying to remember it. You’re hunched, slack-jawed. What’s going on? Is this some kind of dementia? Alzheimer’s?”

Sound familiar?

That is, have you read the above paragraph before? It was posted here a week ago, on an entry about sleep. If you read it then and can remember it now, chances are you’ve slept a few nights since that first reading. And the same chemical that made you sleep probably helped you remember what you’d read.

Sleep and memory are inexorably linked, something scientists have theorized since the early nineteenth century, and tested as early as the 1920s. A study in 2006 found that the brain replays past events during sleep: rats where run through a maze, and brain scans during the run and while sleeping showed duplicate brain patterns. These patterns were occurring between the brain’s visual centers and the hippocampus; while the rats slept, visual memories were being moved from short-term to long-term memory (and, interestingly, the memories were played backwards).

Melatonin is essential to sleep, but the connection between melatonin and memory isn’t spurious. Your pineal gland produces melatonin, which causes drowsiness. While you sleep, melatonin acts as a powerful antioxidant, “washing away” free radicals, (including toxins associated with Alzheimer’s). This action is part of the process that allows for that “dialogue” between the visual cortex and the hippocampus.

Nutshell: As your eyes are exposed to less and less blue light at the end of the day, the pineal gland responds by producing melatonin, which makes you drowsy; and as you sleep, melatonin removes free radicals and facilitates the movement of experiences into long-term memory.

(And one theory holds that we experience this memory storage as dreams—and if the mechanism is not interrupted, you tend to wake up without any memory of dreaming, since the experience of dreaming is a separate conscious observation from the experiences that you were dreaming about—and there’s no “reason” to remember those temporary observations).

If you don’t remember the first paragraph, above, don’t worry: your brain encounters millions of pieces of data every day, and you can only process so much.

But if you want to make sure you do remember for later, why not sleep on it?