Can a Night of Bad Sleep Ruin Your Workout?

by | Building Muscle, Exercise, Fitness, Recovery

Tossing and turning all night. Your mind racing through a hundred different thoughts. Going from being calm to frustrated. And all the other nuances of human emotions. Occasionally starting to drift into unconsciousness. But always returning back to wakefulness.

Morning comes. You feel like you’ve been hit by a freight train. Maybe you did get some sleep. But it’s a far cry from the ideal 8 hours. You’re groggy, tired, irritable, and distracted.

Today is gym day. And you don’t have the slightest idea if you can or should workout.

What Happens When You Don’t Get Enough Sleep?

Sleep aids many vital processes in the body [1]. Examples include:

  • hypertrophy (muscle growth)
  • cell damage reduction and repair
  • glycogen replenishment (storing energy for later use)
  • motor pattern memorization (technique improvements)
  • up-regulation/down-regulation of certain hormones
    • responsible for positive mood and growth
    • responsible for mental stress and fatigue

Some processes are more susceptible to sleep disturbances. Minor reductions in sleep can easily affect your mental state. You’ll notice changes in mood, concentration, decision making, and willpower. Also, the perception of tiredness and motivation.

As sleep time decreases physical performance also starts to deteriorate [2]. Speed, power, strength, and endurance are negatively affected. Chronic sleep issues can lead to muscle loss [3].

However, a single night of bad sleep is not a cause for concern. Most of the consequences are limited to the perception of fatigue and training desire. Yet, that can still cause issues.

How Sleep Deprivation Affects Training Performance

It may feel like your workout will be a total disaster. However, your performance will probably match that of previous workouts [4] [5]. Training will surely feel harder. You may have to use a lot of willpower and rest longer. Or rely on more caffeine. But that’s about it.

Explosiveness, velocity, 1 rep max strength, reaction time, and coordination might also be impaired [6]. But all these have minor impact if you’re a recreational lifter. Weights and reps should remain the same.

If you’re getting too beat up there could be other factors at play. Maybe you had multiple nights of bad sleep. Or you got pre-exhausted due to engaging in other activities. Highly stressful events can also ruin your workout.

Bottom line: Perception is skewed. Skipping a workout or taking it easy may be tempting. Start your workout regardless of how you feel. If performance is okay, keep going. But if you can’t hit your normal rep range, then you really need to rest.

A Note About Sleep Trackers

Some smart devices can evaluate sleep duration and quality. However, take that information with a grain of salt. The accuracy of most sleep trackers is far from reliable [7].

It’s not uncommon for wearable devices to underestimate the duration of deep sleep. The app may advise against heavy training. But you may be able to finish your workout without any issues.

Do You Lose Muscle If You Stay Awake All Night?

No. Not unless you miss more than one night of sleep. Acute insomnia can easily lead to muscle loss. Especially if you’re dealing with starvation, extreme physical exertion, and overwhelming stress levels.

A single night is usually not a problem. Though if mood and discipline are affected you may skip your workout. Or make bad diet choices. Decisions that may impact the rate of muscle and fat change.

What’s the Difference Between 4 and 6 Hours in Bed?

A couple of hours won’t make a huge difference. But there’s a clear dose-response [8], [9]. The more sleep you get the better. Though different biological systems are affected in different ways [10].

Context: A single night of poor sleep. Normal rest patterns during the rest of the week. 

  • Wakefulness and perception of fatigue: A sleep cycle lasts 1:30 hr. When you wake up at the end of a cycle you feel refreshed (e.g. 1:30 or 3:00 hrs). If an alarm interrupts deep sleep you may feel groggy (e.g. 0:45 or 2:00 hrs ). This sensation won’t last the whole day. Yet, it can influence early training.
  • Cognitive performance: Alertness, attention, and concentration decrease with sleep time. Though the cognitive demands of a normal workout are not great. But you may get easily distracted in the gym. Getting less sleep might lead to longer workouts.
  • Motivation and training desire: Minor changes in sleep time rarely affect short-term motivation. Long-term commitment takes a hit first. You may still be motivated to train today. But get complacent with exercise form. Not caring about the injury risk. Or the potential consequences for future workouts.
  • Physical performance: Almost no difference between 4 and 6 hrs. There are exceptions though. Let’s say you had a brutal workout the day before. A bit of extra sleep can have a notable effect on next day’s performance.

Which Is Worse: No Sleep Before or After a Workout?

“After”. You reap most of the benefits of a workout during sleep. Pulling an all-nighter after an amazing workout can render the session pointless. Poor sleep reduces the rate of protein synthesis [10]. You grow less muscle.

What if you train sleep-deprived? You may have a subpar session. Provide less muscle stimulus. But at least all that stimulus can be translated into gains. Assuming you catch up on sleep after that.

Common Sleep Issues

Sometimes you can’t sleep for no apparent reason. If it rarely happens, it’s probably nothing to worry about.

Often you can track the issue to a specific cause:

  • Physical stress (overwhelming exhaustion) – Pushing your body to its limits can affect sleep. Especially if it happens close to bedtime. Or if you experienced multiple days of fatigue accumulation.
  • Mental stress (worry, anxiety, etc.) – Anything that puts your mind in a hyper-aware state can keep you awake. You’re likely in a flight or fight mode. Your brain is staying alert and awake as it anticipates danger.
  • Environmental distractions (lights, noise, temperature) – This point is pretty self-explanatory. A number of factors can affect your sleep time. Usually, you’re well aware of the exact issue.

How to Have a Great Workout Despite Feeling Terrible

Assuming you don’t have a serious chronic sleep issue, here’s what you can do:

Take a nap – Your first option is a 20-30 min power nap. Enough to improve how you feel. Not enough to enter deep sleep. You can also go for 1:30 hr. Anything in between 30 to 90 mins means you’ll wake up in the middle of deep sleep. You’ll feel groggy initially. Though once the sensation wears off energy may improve later during the day [11].

Get some caffeine – Caffeine doesn’t directly improve performance. But it affects your mood. Given the effects of short-term sleep deprivation, a cup of coffee is a great solution. Up the dose if you normally drink coffee before training.

Skip the session – You can move your workout to a different day. Or do a different session. Something easier. Not a bad idea if you have a hard workout planned. An occasional re-ordering of sessions won’t have a big impact on long term progress.

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Until next time!

~Niki, Fitness Mastery Coach

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