How did you sleep last night? It’s day 4 of the 10x10 Sleep Challenge and I, for one, slept better than I have in months. Hopefully, you saw a similar improvement already. We talked the first couple of days about getting started and obstacles to the process. Today we’re talking chemistry, biology, and substances. Don’t worry, this won’t be a mind-numbing science lecture.

In the book Head Strong, Dave Asprey shares some information about sleep and melatonin. Melatonin is a hormone our bodies make by breaking down serotonin. Without enough melatonin it could be harder to fall asleep and you’re less likely to reach the deepest levels of sleep in your cycle. This means you don’t get the most valuable and restorative phase of sleep. In case that wasn’t a big enough red flag, let me approach this from a different angle. You can get more benefit by reaching the deepest phases of the sleep cycle than by increasing the number of hours you sleep. This is your 80/20 of sleep. Quality over quantity matters in sleep too.

According to the National Sleep Foundation, melatonin is the only hormone available in the U.S. without a prescription because it naturally occurs in some foods. You need to hear something, though, before you run out and buy some pills. The Sleep Foundation, National Institutes of Health, and others warn that the use of this supplement is not fully understood. It can even hurt your sleep cycle if not taken in the right amounts at the right time of day.

The good news is the body has natural systems for the release of melatonin. Hint: tomorrow we’ll shed more light on this.