If there’s something I’ve grown to understand a little too well over the past few months, it’s the effects of sleep deprivation. Ten months ago, my wife and I were fortunate to welcome our beautiful baby daughter into the world… and I don’t think we’ve had a full night of sleep since. But perhaps I can take comfort in the fact that hundreds of other men share in my plight. Fellow dads? No, major leaguers. Now that we’ve started the season, let the sleep deprivation begin!

Baseball is unique in that it’s a daily sport. Football games come but once a week. Basketball and hockey players might play three or four games within a week. Further still, even when basketball and hockey teams play two nights in a row, it’s very rare that they would play a game 15 hours after finishing the previous one. In baseball, this is known as "Sunday." In football or basketball, a player might not play because of an injury or because his performance has been awful, but it’s unheard of in those sports for a player not to play in a mid-season game "because he needed an off-day." Teams in other leagues usually practice every day, but the thing about practice is that it doesn’t count in the standings. Baseball players have to be ready to go every day, and so in baseball, rest is at a premium.

In some ways, baseball is also a game that is set up to reward the well-rested. All sports involve physical effort, which of course will be affected by fatigue. But baseball demands additional skills, like extended concentration, from its players. Players spend extensive amounts of time waiting for something to happen, but not being entirely sure when it will, and that’s hard to do when you’re tired. In basketball and hockey, there is a good chance that you will be given the ball/puck at any moment. In football, during every play, there’s a job for each player. In baseball, there’s no telling when you might be called on to make a catch. But when it happens, you need to react quickly, and you can’t have fallen asleep in the field. That sort of concentration is hard to maintain when well-rested. Have you ever been in a really boring meeting, but one where you knew that your boss might call on you and you’d have to look semi-intelligent? Ever do that meeting after a night where you didn’t sleep well?

I’d contend that there’s a(nother) hidden skill in the baseball toolbox. It’s so hidden that it doesn’t happen on the field, is rarely discussed, and few people fully understand its importance, yet it has a great deal of impact on a player’s performance. I’m talking about sleep hygiene. (Let me guess, you’ve never heard that term before. Don’t worry, most people haven’t.) How good is a player at regulating his sleep? Given what we know about sleep, the answer might be more important than you might think.

Let’s talk about what makes for good sleep hygiene. It’s more than just getting a certain number of hours of sleep (although that is important.) It’s about making sure that the body is put into a state where it can get good sleep. (And yes, there is not-so-good sleep.) The first thing to know is that the sleep cycle starts well before you even get into your pajamas. It begins about half an hour before you lay down. Most people have a before-bed routine (brushing your teeth, washing your face, etc.) that you do, which serves the dual purposes of keeping you clean and telling your body "it’s time to go to sleep." It’s a bad idea to do things that get the body all worked up before going to bed. Some people say that they work out right before bed in an attempt to tire themselves out. The problem is that you end up turning all the neurons and muscle fibers on during the workout, and your body has to work longer to turn them all back off to go to bed. Because the body works on a 24-hour cycle, it’s also best to try to go to bed and wake up at the same time each day. This will ensure that the sleep that a baseball player (or a non-baseball player) gets is good, restorative sleep.

Now let’s think about what actually happens in baseball. Teams travel a lot, so it’s hard for a player to get into a good bedtime routine because he will sometimes move from hotel to hotel over the course of a month. His job takes place most often at night, with a 7 p.m. game ending at about 10 p.m. or 10:30 p.m.. Figure in a post-game shower and travel time, and he’s probably getting back to his house or hotel room at 11:30 p.m. Then again, let’s be honest. We’re talking about a group of mostly 20-something guys who have six- or seven-figure salaries and been sent by their company on a three-day road trip for work. What do you suppose some of them do after the game? Suffice it to say that they’ll be getting back to the hotel a little bit later than 11:30 p.m. (to say nothing of any other activities in which they might take part in at night.)

Baseball is set up, particularly for road teams, to interrupt several factors that make for good sleep hygiene. No wonder baseball players describe the playing of a season as a "grind." They’re probably tired a lot of the time, and life isn’t fun when you’re constantly tired. But other than a little fatigue, is this something that teams, players, and fans need to worry about? It’s nothing that a little caffeine won’t fix, right? Wrong.

Sleep does several things for the player, both physically and mentally, such that a player who is good about his sleep hygiene is going to have a significant advantage over his counterpart who stays out all night and "gets by" on a few hours. What’s more is that a player might not even know that he is being affected. In a recent study, volunteers who had gotten a proper amount of rest (this varies from person to person, but in general seven to eight hours per night is a good guideline) on a consistent basis were matched up with those who had consistently gotten a mere hour less than the recommended level. (These aren’t the wild partiers, just the people who just had to stay up to watch that re-run of Full House at midnight.) The two groups reported no difference in how rested they felt, but the group who had gotten enough rest showed superior performance on a number of mental tasks, including pattern recognition and response time tasks. These are the same skills that are controlled by the pre-frontal cortex and pattern recognition is key to a player’s ability to figure out what pitch might be coming next ("he likes to throw fastball then curve… he might do it here…"). The effects of reaction time should be fairly obvious.

During sleep there are a few other important things that happen:

  • Muscles that have been worked out have a chance to build additional muscle fibers and create new blood vessel pathways. This is why good sleep is important to any workout regimen. The body isn’t just resting, but developing.
  • Lessons learned during the day appear to be consolidated during sleep, probably because the brain has a chance to build and strengthen pathways while the body is asleep. So, if a player learned something that day, it’s the brain’s chance to catch up to integrate that knowledge into what a player already knows. This, by the way, is one theory of why dreams happen.
  • Neurons in that pre-frontal cortex that control all the cool cognitive things that humans can do get a chance to rest and reset. When these aren’t working so well, the effects are much like alcohol intoxication, primarily because alcohol shuts down that part of the brain first. As a result, players are better able to identify patterns, solve problems, and regulate their emotions.

Sleep is about much more than resting physically. It’s the body’s chance to repair, renew, heal, and (surprise!) improve. And you thought it was just a time of passive unconsciousness. A player who is not good about his sleep will miss out on many of these benefits, not to mention be grouchy in the clubhouse. It’s an effect that might not appear after one bad night, but over the grind of a six-month season, it might be the difference between a player who is able to fully leverage his impressive physical talent and a player who is not.

There’s a great deal made about whether a young player is a good "character guy" within the scouting community. "Character" is a hard-to-define, fuzzy word, and can indicate a number of things, which is why I think that sabermetricians have shied away from it. Generally, it means "what a player does when he’s not on the field" and it might be a decent proxy for whether a player has the good judgment to look after himself both on and off the field. But more than just being an indicator of how likely a team is to deal with embarrassing PR messes, it might actually tell us something a little more direct about what we can expect from a player’s development and his on-field performance. If a player is the type who gets his sleep, an organization can expect to see him get more out of his talent level. The problem with measuring sleep hygiene is that the only way to reliably do so involves following players back to their homes and hotel rooms… in other words, engaging in stalker-metrics. Perhaps further research can turn up some decent on-field proxies for such issues as sleep hygiene, but for now, sabermetrics is faced with a rather interesting problem. There is a variable which I hope I’ve made the case is rather important to a player’s performance and which currently, we have no way to measure.

Special thanks this week to my wife, who took care of our daughter while I napped and cured my writer’s block.

Thank you for reading

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Interesting article, and great to see this kind of alternative analysis.

This has interesting implications for west coast teams traveling east, and vice versa. The NBA's Trailblazers are, I think, the only team that's actually taken a look at it.
Maybe this is why Dan Haren struggles in the second half, but Adam LaRoche and his ADHD get worked out after the first half.
Interesting article; I'd be really curious to see how to quantify some of this - for example, are some players worse at getting and staying to sleep? Is this something you could test by getting potential draftees to spend a few nights in a sleep lab?
You could screen for sleep disorders with a sleep study, but mostly, this is behavioral, such as picking a good bed time and sticking to it.
All the star player should be given a sleeping (oxygen?) chambers to ensure good sleep(the one MJ got). Good article! I think it can be a new black... I remember Beckett has had neck problem and "sleeping on my right arm" problem before.
This is exactly what my mother said when I was seventeen. And despite my good character (I've always been a "character" kind of guy) she might as well have been talking to a bag of rocks.