If there’s any athlete that it would be impossible for me to care less about, it would be the boxer Floyd Mayweather.

Don’t get me wrong, he’s incredible. I just find it hard to stomach his antics and personality.

Yet one thing that he said has always stuck with me.

Way back when I was in university (which shows you how long Mayweather has been competing), I remember reading that he sleeps 12 hours a day in order to recover and prevent injury.

Now at the time I was likely sleeping 12 hours a day as well. I wish I could say it was because I was an elite athlete. Instead, it was because I was a typical Canadian university student.

I’ve always wondered if sleep is responsible for his incredible longevity and lack of major injuries.

Let’s contrast Mayweather with some other notable figures like Thomas Edison who famously slept 4 hours per night, or Bill Clinton who grabbed just 5 hours per night of shut eye.

With such a broad range of these high performers, what is the optimal amount of sleep?

(side note – in University my housemates and I learned about Polyphasic sleep in a psychology class and thought it would be perfect to try at exam time to maximize cramming. This method sees you stay awake for about 3 hours, then sleep approximately 20-30 minutes, repeating it ongoing throughout the day. Needless to say this was a VERY poor decision).

Currently, I feel AMAZING if I get 6.5 hours of sleep a night. (I am going to take this opportunity to place most of the blame on having 3 young kids).

Interestingly I also find I am getting injured more frequently with my athletic endeavors.

I am now officially 40 years old and have been refusing to blame this for my aches and pains associated with exercise routines I did in my twenties with no issue.

So I was EXTREMELY happy to see a recent article from February that summarized the association between poor sleep and injury incidence in sport.

I guess my hope was that I can blame my increased aches on poor sleep.

This article is a systematic review with meta analysis which essentially means it is a summary of the best prior articles on sleep and injury prevalence.

Sleep deprivation triggers changes that could contribute to injuries.

• Testosterone and growth hormone are needed for protein synthesis (which is needed for recovery), yet sleep restriction for just 1 week leads to a significant reduction in both.
• In contrast, cortisol, which is a catabolic hormone (meaning it breaks things down) is released in higher concentrations after just 1 day of sleep disruption.
• Previous studies have showed a negative impact performance with poor sleep for anaerobic power, cardiovascular endurance, maximal strength and it also delays muscle recovery.
• Poor sleep will alter the quality of your dietary intake.

 

Sleep is in the spotlight enough that there are now positions statements on sleep from the NCAA, the International Olympic Committee, and the International Congress on Soldiers Physical Performance.

 

So did the findings in this article blame sleep for my increased injuries like I hoped?

 

Not exactly.

 

The review ended up summing the evidence from 12 articles that met their inclusion criteria. The articles were taken from a broad range of sports. They were extremely variable in many aspects including how they actually measured sleep, the study follow up period, and even how they defined an injury. This variability makes it hard to draw concrete conclusions.

 

As an example one study looked at cross country runners and found the risk of suffering an injury was less among those that reported better quality sleep. That’s great, but when you controlled the study participants for the differences in mileage and the presence of a pre-season injury, the sleep data are no longer meaningful.

 

Six of the twelve studies did show an increased risk of sport or physical training related injury with poor sleep quality, but only 2 still held that association when other variables were controlled for.

 

Overall, the association was concluded as weak and inconsistent.

 

So where does that leave us?

 

Injury is a very delicate topic and has a variety of variables as contributors. Diet, training volume, training surface, past injuries are just a few items that come to mind. Layer on top of that sleep hygiene and you can see that it is difficult to tease out just one item.

 

The data on sleep is very limited in adults. In researching this article, I came across some writing from Alex Hutchinson. In his article he put up the following figure, taken from a very widely cited study on 112 adolescents from a single Los Angeles high school.

The same image was used in Michael Walker’s extremely popular book called “why we sleep”. The kicker? Alex notes that Walker OMITTED THE 5 HOUR DATA FROM THE GRAPH!! I guess in his book, to make a point he wanted to show a straight line correlation as it would make his point more succinctly.

The lesson? In Sports Medicine drawing conclusions on something as complex as injuries is not always that simple. Also, don’t be too hard on yourself if you get a poor nights sleep. It’s very unlikely that it is the singular contributor to any injuries you may sustain.

Now don’t mind me but my wife is at the park with the kids……..I’m going to try and take a nap.