Whether it’s drinking a glass of raw eggs  or doing 100 pushups by 4 am every day, some athletes will do whatever it  takes to get a competitive advantage.

And some professional sports teams go to similar lengths to get the  most from their athletes. That’s why teams like the Atlanta Falcons  and Seattle Mariners have revamped the lights in certain parts of their stadiums  to optimize their players’ performances.

It’s called bio-adaptive lighting, and the  idea is to use a certain kind of light to adjust the athletes’ circadian rhythms to  the time of day when they’re at their best. But is this idea a home run? Or a swing and a miss? [♪ INTRO] Many of us are familiar with  the early afternoon slump.

That time right after lunch where  a nap is just calling your name and you’re fighting for your  life just to stay awake. But other times of day, you’re a working machine! Creativity, energy, and motivation galore.

Well, just like the rest of  us, professional athletes have certain times of day  when they’re at their peak. This goldilocks time varies  based on the person or the sport, but the consensus is that  athletes are often at their best in the late afternoon and early evening hours. During that sweet spot, studies show  that soccer players juggle better and score more goals, cyclists bike  faster, and basketball players jump higher.

So if we wanted to see athletes at their  best, then every professional sporting event would be held at that time of day. But unfortunately, that’s not how it works. And the key player here is the  athletes’ circadian rhythms.

You’ve probably heard of circadian rhythms before, maybe in the context of jet lag  or your late nights as a teen. It’s the natural, internal clock  that all of us are built with. Even when we aren’t aware of it,  multiple systems in our bodies are operating under the guidance of this rhythm.

For example, at night your circadian  rhythm tells your metabolism to slow down, which is why eating a huge meal right before bed can mess with your sleep and increase fat storage. And as weird as an abstract sense of time  in your body sounds, it’s very much real. In fact, there are a bunch of genes  that code for this biological clock.

Essentially, a bunch of our  organs have this ticker, and a master clock in our brain  exists to coordinate them all. And according to research, it’s that clock that dictates what time we’re at our  best. Including athletically.

One easy way to see this is with  traveling teams in the United States. Because the west coast and east  coast are 3 time zones apart, a team's performance can be judged  based on the time zone they’re in versus the time their circadian rhythm thinks it is. And we can see patterns.

A study from 2013 in the Journal of  Sleep examined more than four decades of professional American football games,  comparing the performance of teams from the west and east coasts when  they competed against each other. Day-time games, defined as starting  at 1pm and 4pm Eastern Standard Time, were used as the control, while night-time games, or those after 8pm Eastern,  were the focus of the study. They took into account the different  abilities of the teams using a sports-betting metric known as point spread, and checked how often the teams from  the two coasts beat their odds to win.

And they found that west coast  teams beat those odds significantly more than the east coast teams  did during the evening games. This makes sense for two reasons. First, when the games were played on  the west coast with an 8pm start time, the east coast team was at a severe disadvantage since their circadian rhythm  was thinking it was 11 pm.

But that’s just the start time. I don’t know about you, but  in the middle of the night, the only running I can do  is running out of energy. The other reason it makes sense that  the west coast teams did better is because when playing on the east coast at 8pm, their internal clock is set to 5pm, which  is close to their peak performance time.

Either way, the west coast teams had an advantage over the east coast teams for  any games later in the day. And there was a ton of data, so the statistical significance of this study was very high. For the stats folks out  there, usually a p value of less than 0.05 is statistically significant.

This study had a p value less than 0.0001. Those are MVP numbers in this area of math. The researchers concluded that east coast teams would benefit from delaying their  circadian rhythm by about 3 hours.

Which gave some lighting companies  and sports teams an idea. One major thing that we know  affects our circadian rhythm is the amount and type of light we receive. So it’s not a huge leap to think  that we can use light to manipulate an athlete’s circadian rhythm,  ideally making those night games feel more like early evening games and  getting to see everyone’s top performance Over the last decade, several teams have  revamped the lights in their locker rooms and other team areas in the  hopes of doing just that.

The main difference between  regular lights and the lights these companies use is that  the new ones are tunable. Teams can adjust the intensity  and temperature of the lights. Specifically, the new setups use  blue-enriched lighting to suppress melatonin and mimic daylight before a game.

Then they can be adjusted to  warmer, dimmer lights after a game to help stimulate melatonin and  get players to sleep faster. But the big question is: does it actually work? And science says… maybe?

It’s kind of a three part question. First, do circadian rhythms  affect athletic performance? And the answer to that is yes.

Research shows that circadian late  afternoon and early evening are best. Second, can lights be used  to retrain circadian rhythms? And third, if lights can retrain these  rhythms, will that improve performance?

To that second point, there’s  a bunch of data out there on how the circadian rhythm  can be retrained with light. A lot of this research is on night shift workers, the people who keep the world  running while the rest of us sleep. Using temperature and  salivary levels of melatonin, researchers can track how light  affects the circadian rhythm.

Several studies have found that brighter  lighting during the shift and a lack thereof on the drive home is able to delay or even  flip night workers' circadian rhythms. And that comes with some perks. For example, when the circadian  rhythm aligns with the night shift, workers report better sleep and mood.

Plus, their performance is significantly  better with these light adjustments, too. So lighting is effective at  shifting our circadian rhythms, and being in tune with your circadian  rhythm can help your performance. But making that last link of  retraining athletes’ circadian rhythms with light and improving their  performance is the hard part.

So far, there haven’t really  been any formal studies on this new lighting in stadiums  or how it affects players. The science of lights suppressing melatonin  and improving performance is there, but the research putting it all together isn’t. The companies are mostly relying on  the idea that blue-enriched lighting can increase alertness, but most of  those studies weren’t done on athletes.

And the few that were had mixed  results, finding that light exposure does decrease melatonin levels but doesn’t  necessarily affect athletic performance. Plus, since the lights are adjustable  with tons of different settings, they aren’t easy to study  outside of a lab setting. Still, a few teams have already spent a  lot of money on bio-adaptive lighting.

And it’s not just sports organizations. Schools and office buildings have, too. Anecdotally, some claim  that these lighting systems reduce headaches and improve performance.

But again, there is no formal  research supporting this. This practice kicked off a decade  ago, so hopefully new research will shine a light on whether this  actually helps teams win more games. But if your team is lousy, I wouldn’t  count on the light bulbs changing that.

This video was inspired by The Inner  Clock, a new book by Lynne Peeples. It’s all about circadian  rhythms, and the surprising number of ways they affect our lives. If you’d like to check it out,  head to the SciShow Bookshop page.

Thank you to the Alfred P. Sloan  Foundation for making this video possible. [♪ OUTRO]