Sleep: a new vital sign

The surprising way sleep, or lack thereof, is affecting your health and performance

Through every race, training run, recovery session, and every moment in between, the heart muscle gives a steady, oxygen-delivering beat to life. 

Simply put, heart health is vital for daily function and athletic performance. 

So, what’s the most important way to care for your heart?

More obvious answers are eating well, exercising, and not smoking. While all of these are true, there is another significant emerging factor to heart health: sleep. 

”Any form of missing out on sleep is not good for cardiovascular health,” Brady Holmer, a doctoral candidate in applied physiology at the University of Florida, said. 

Holmer performs research that focuses on the impact of exercise and lifestyle factors, like sleep, on cardiovascular health and function. He’s also a runner and self-proclaimed performance geek. 

As a collegiate Division 1 runner, Holmer credits his interest in exercise science to his love of running. He competed for four years at Northern Kentucky University and has competed multiple distances post-collegiately. After undergrad, the opportunity presented to work in cardiovascular research.

“My running piqued my interest in (exercise science),” Holmer said. “For cardiovascular function, it was more a situation of opportunity. I more so fell into this research area. I ended up loving it and it’s the perfect research area for me.” 

Needless to say, Holmer knows the cardiovascular system very well and his research goes, well, deep.

It’s the inner layer of blood vessels, the endothelium, that is the focus of Holmer’s systematic review¹, which supports a correlation between sleep deprivation and endothelial dysfunction. 

The endothelium lines the deepest layer of blood vessels, Holmer explained. It releases various molecules to cause a blood vessel to dilate to deliver more blood to your body and brain while exercising. 

While studying and explaining cardiovascular function can become complicated, the bottom line of Holmer’s research is pretty simple. 

Sleep deprivation, even in small doses, is bad for your heart and running performance. 

One of the main points of Holmer’s systematic review is that people who sleep less than 7 hours per night, compared to those who sleep 8-10 hours per night, have lower endothelial function than their well-rested counterparts. 

“What we found is that in healthy younger adults, it is pretty consistent that if you stay up for even a single night, you are going to have reduced endothelial function the next day,” Holmer said. “Your body won’t be as efficient as distributing blood around your body compared to if you were well-rested.” 

But there is good news for active people who are short on sleep. 

“On the bright side, if you get a night of sufficient sleep, after two nights of recovery sleep, your endothelial function will be back to normal within the day,” Holmer said. 

Holmer further explained that there are things you can do to actually prevent short-term endothelial dysfunction, and one of those things is exercise. 

“If you’re exercising before or after sleep deprivation, your endothelial function will be normal,” even after missing a few nights of sleep. Holmer said. “If you’re going to cram for an exam, make sure you exercise that day to lessen the short-term effects.”

While this is encouraging for times when you know you’ll lack sleep, it isn’t a long-term strategy.

“The point to underscore is that sleep is important so you can function normally,” Holmer said. “If you’re someone who enjoys exercising and working toward a goal, lack of sleep will reduce your motivation; it is important for cardiovascular adaptations. 

If you’re not sleeping and you’re exercising hard, you’re going to be impaired. I would venture to guess it’s going to inhibit your gains from exercise, whether you’re in (physical therapy) or trying to peak for performance.”

1. Holmer, B.J., Lapierre, S.S., Jake-Schoffman, D.E. et al. Effects of sleep deprivation on endothelial function in adult humans: a systematic review. GeroScience 43, 137–158 (2021). https://doi.org/10.1007/s11357-020-00312-y

Katie Noble is a Doctor of Physical Therapy, a journalist, and a runner. She enjoys empowering and supporting female runners with evidenced-based education.