How Does Sleep Affect Your Exercise Performance

A few weeks ago I was asked to contribute to an Argos article about ‘How to Perfect the a Good Night’s Sleep’ and wrote about how fitness helps me sleep better – I always sleep deeply when my body is exhausted! However I try to avoid anything too high energy late at night as it works as a stimulant and keeps me awake, opting instead for low impact workouts.

Thinking about sleeping and exercise had me thinking about how sleep affects exercise performance.

how sleep affects exercise performance

They say that two nights before your marathon or goal race is the night where sleep counts the most. Pre-race nerves, an early start and carb loading will probably affect the night before your race more than you know, and so it’s important to log those hours in the days leading up to your run.

But what about the weeks beforehand, the months of early morning training runs, of foam rolling late into the night. What do you think happens to your body when you put it under immense stress and then don’t treat it to enough hours of zzzz.

According to the US National Sleep Institute, the quality and quantity of sleep that athletes get can often be the key to winning. REM sleep (rapid eye movement sleep, accounts for about 20-25% of our total sleep time) is the most important in terms of providing energy to the body and brain. Quality sleep improves decision making skills, accuracy and crucially for athletes (even recreational athletes) helps the body to maintain speed and endurance. Not to mention the muscle recovery that occurs whilst we’re sleeping.

Studies have also shown that a lack of sleep can increase the body’s production of the stress hormone, cortisol, plus a decrease in production of glycogen. In fact in just four days of sleep deprivation, your body’s ability to use insulin properly becomes disrupted – not what you need when you’ve got marathon hunger already!

How sleep affects exercise performance

Got a hard speed set to complete, or a long run? Well, research suggests that sleep deprived individuals are more likely to give in impulses, have less willpower and self control, meaning that you’re more likely to quit on those Yasso 800’s before you’re finished.

At this time of year, with the temperatures dropping, it’s important to keep you immune system strong. Sleep deprivation decreases your body’s ability to fight infection, meaning you’re more susceptible to the office cold when you’re tired. Sickness can play havoc with your training plans, and your workout performance in itself. Another surprising side effect of lack of sleep is the effect it has on your ability to sweat, reducing your body’s natural air conditioning system.
Luckily, for most people, when they’re training hard they find it easier to fall asleep at night. We should be aiming for around 8 hours of sleep a night, which means going to sleep at 10pm if your alarm will be going at 6am for your training run. Try not to have too much caffeine before bed, and create a calm, organised bedtime routine.

Photos by Will Patrick. Wearing Sweaty Betty run kit, Adidas Ultra Boost trainers.


  1. February 2, 2016 / 10:22 am

    Great post Charlie! I’m in training for my first marathon so getting enough sleep is top on my priority list, this articles just reminds me of why. Your post about supplements was also useful, I’ve already been taking a multi-vitamin every day but you reminded me about magnesium that I ran out of and never replaced. I suffer from frequent headaches and someone recommended taking that to help- it did seem to.

  2. healthyhappierbear
    February 2, 2016 / 1:59 pm

    Love this reminder that sLEEP is super important all year long, not just before a big race!

  3. February 2, 2016 / 3:05 pm

    Sleep is definitely something I’m NEVER good at prioritising! Must try harder…

  4. February 2, 2016 / 5:58 pm

    Interesting about the knock on effects on the body’s cortisol and insulin levels…

  5. February 3, 2016 / 2:46 am

    I can’t remember the last time I got a good nights sleep…maybe before I was pregnant. A year a half?? It’s so important. Living in a state of perm-exhaustion can really take a toll. I love that run kit!

  6. February 3, 2016 / 2:50 pm

    I would imagine that getting too much sleep could affect performance as well. Either way, I try and aim for 7+ hours of sleep each night.

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