We all know that sleep is important for our health, fitness and wellbeing. Not only do we feel groggy and lethargic if we don’t get enough, but we’re bombarded by so many articles reminding us of the links between sleep, recovery and improved performance. We should know, we’ve written a fair few ourselves.
That’s all well and good knowing the theory. But I was interested to find out exactly what difference getting the ‘right’ amount of sleep makes for me – just how much of my fitness am I really sacrificing when burning the midnight oil?
To find out, I used a combination of Garmin’s Fenix 7 smartwatch to track my resting heart rate, heart rate variability and other variables. I also performed a series of fitness tests on the turbo to track what was happening to my power and heart rate numbers.
Then, it was a simple case of allowing a series of bad nights’ sleep and conducting the first tests. I followed that with a series of nights in which I got at least the eight hours of sleep that Garmin recommends, and conducted the final tests after that.
The results were quite interesting – particularly that my heart rate was typically suppressed for any given power when I wasn’t adequately rested. Just glancing at the numbers, it would be quite easy for someone to mistake that for an improvement in fitness – a lower heart rate for a given power can mean that your body has become more efficient and you’ve become fitter.
But a closer look reveals the tell-tale signs that everything is not as rosy as it appears, and that I was carrying some heavy fatigue.
So, without further ado, let’s dive into the numbers and the tests I performed to see just what difference getting a full eight hours made to my riding.
Power tests
First, I needed to choose what power test I was actually going to conduct. A straightforward FTP test on Zwift would be the most obvious, but there are myriad of factors that can affect the outcome of a maximal, all-out test – it would have been too easy for something to end up skewing the results.
With that in mind, I opted for two sub-maximal power tests. These would show the relationship between my power and heart rate numbers without introducing other, more nebulous, variables such as motivation or pacing.
The first was the Lamberts Submaximal Cycling Test (LSCT), and plain and simple two hours of Zone 2 (sub lactate threshold 1) aerobic endurance. Both were conducted with a heart rate monitor and power from a Wahoo Kickr V5 with