Thirty years ago, we thought we had a lot of things figured out -- just look at '80s fashion, as the video above points out -- but in retrospect, we certainly didn't know it all.

One pretty terrible mistake? Our collective bedtime philosophy was "sleep is for the weak."

Now we know that getting too little rest doesn't do us any favors. Research continually shows "cheating the system" by skipping sleep in order to have more hours in the day is detrimental to our health .

For our second episode of Next Level Living, a 10-part HuffPost Originals video series on the science behind our everyday habits, we explore what's going on in the body when we're asleep -- and why it's so crucial to how we operate when we're awake.

We may look peaceful when we're snoozing, but it turns out our bodies are actually hard at work. We cycle through four stages of sleep, which we repeat four to five times in an eight-hour night. It's a process that has aided in our evolution as human beings, even dating back to the time of cavemen. When our sleep is interrupted -- or worse, we don't get any at all -- it wreaks serious havoc on our body and mind when we're awake.

Luckily, there are easy wasy to prime ourselves for an ideal night's rest. Take a look at the Next Level Living episode above to learn how you can sleep soundly and to find out how we evolved to prioritize those Zs.

To view previous episodes of Next Level Living, head over here .

Also on HuffPost: