We all know that sleep is essential. Yet, many people fail to get a good night’s sleep. But why is that?

One reason is that we are good at passing the responsibility to our future selves. “I’ll catch an extra two episodes of my show, and I’ll worry about sleep deprivation tomorrow.” Another reason is that we don’t genuinely understand the drawbacks of not sleeping, especially related to our fitness progress.

So, while I can’t comment on the former, I can share four ways in which not sleeping is ruining your progress.

1. Increased hunger and cravings

A huge reason why sleep deprivation prevents you from reaching your goals is that it increases your hunger and cravings. For example, in one review from 2019, researchers found that sleep deprivation increased subjective hunger and caloric intake (an average of 250 extra calories/day) (1).

Another review had similar findings (2). Across 17 studies, subjects who slept less (an average of five hours per night) consumed nearly 400 more calories each day.

A more recent review had the same findings as previous papers (3). Researchers found that reducing sleep to 5.5 hours or less led subjects to consume an extra 200 calories daily.

2. Reduced ability to control your impulses

Sleep deprivation makes everything more difficult. Instead of making the best possible decisions for the future, we are more likely to fall for instant gratification (4).

Coupled with the elevated hunger we experience, we have a big problem, especially while dieting to shed some fat. In addition to these issues, sleep deprivation can lead to sleepiness and loss of motivation. As a result, we are more likely to skip that workout in favor of something more pleasurable. 

3. Low energy levels and possibly impaired athletic performance

Sleep deprivation is a bit weird when it comes to our energy levels and athletic performance. On the one hand, not sleeping enough is a good way to ensure that you feel sluggish and weak. But, on the other hand, we also have some research suggesting that not sleeping enough doesn’t necessarily impair our strength, endurance, power, and such (5).

Still, we can all agree that not sleeping enough is not the best strategy if your goal is to perform at your best and make good progress with your training.

4. Possibly impaired ability to burn fat

Sadly for us, not getting enough rest can prevent us from burning fat and might instead cause muscle loss while dieting.

The above effect is something researchers noticed in a 2010 study (6). Ten overweight but otherwise healthy people had to go through two conditions that were spaced at least three months apart. In the first condition, subjects did a diet and could spend 8.5 hours in bed. In the second condition, the participants followed the same diet but could only spend 5.5 hours in bed per night.

The two phases lasted for 14 days each, and subjects lost an average of 6.6 lbs (3 kilos). When subjects spent 8.5 hours in bed (slept an average of 7 hours and 25 minutes), they lost muscle and fat at a 50/50 ratio. But, when they could only spend 5.5 hours in bed (slept an average of 5 hours and 14 minutes), they lost muscle and fat at an 80/20 ratio. With everything else being the same, sleeping less resulted in 1.6 times more lean tissue loss. When sleep-deprived, subjects also reported more hunger and cravings.

Of course, that study isn’t without its issues. For example, their diet was quite harsh and low in protein. But, it did a good job of illustrating the importance of sleep. So, regardless of your goals, aim to sleep for at least seven hours per night. If possible, aim for eight during periods of high stress or more intense training.

Thank you for reading! Until next week,
Philip

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