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Should You Workout After a Bad Night's Sleep?

If you’re the type that tends to work out in the mornings, a common decision you might be forced to make is whether or not to hit the gym after a not-so-great night of sleep. It only takes one bad night of sleep to make your brain feel fuzzy and your muscles feel fatigued. But for some of us, that isn’t enough to make you skip a workout, but should it be?

Unfortunately, turning to Google for the answer won’t help much either- there’s research on both sides of the argument. Some researchers say it’s fine to work out with little sleep, while others say the opposite. In this blog, we’ll break down what the experts are saying, and how you should make the decision for yourself.

What a bad night of sleep will do to your body:

Before delving into how a bad night of sleep will impact your body, it’s important to know how much sleep you should actually be getting. Thankfully, the National Sleep Foundation has published a report on how much sleep you should be getting based on your age:

  • Teenagers (14-17) → 8-10 hours per night

  • Young adults (18-25) → 7-9 hours per night

  • Adults (26-64) → 7-9 hours per night

  • Older adults (65+) → 7-8 hours per night

So, what happens to your body after a night of bad sleep? Studies have found that it only takes one night of bad sleep to cause symptoms like:

  • Anxiety → One study found that after a night of sleep deprivation, participants reported a 30% rise in anxiety levels.

  • Elevated stress levels → A night of bad sleep triggers a stress response in your body, causing elevated levels of stress hormones like cortisol. And, if your cortisol levels are high, your body won’t be able to burn fat.

  • Increased hunger → When you’re low on sleep, your body produces more of the hunger hormone, ghrelin, making you feel hungrier. One study found that sleeping 5 or fewer hours a night can cause you to eat an extra 385 calories per day.

  • Decreased leptin → Leptin is the hormone that helps your body feel full after a meal. A bad night of sleep will leave you feeling less full, even if you eat enough throughout the day.

  • Inhibited brain function → Getting too little sleep will decrease your attention span and reduce your reaction time. This makes you more prone to workout-related injuries.

When to hit the snooze button and get those extra Zzzs:

If you've been working out on little sleep for an extended period of time, it might be smart to skip an early morning workout. As detailed above, getting too little sleep will impact nearly every part of your body in a negative way, so if you’ve had a series of bad nights, it might be best to just skip your workout.

Moreover, if you’re feeling stressed out, might be best to skip the morning workout. Constant stress can leave you with heightened levels of cortisol, which as we know, is bad for the body- causing weight gain, a weakened immune system, and more. And, one of the best ways to decrease your heightened cortisol is by getting extra sleep.

If you’re trying to gain muscle, it also might be best to get a couple more hours of sleep instead of hitting the gym. While you’re sleeping, your body produces human growth hormone (HGH), a crucial hormone to help your muscles recover from the day and grow stronger. One study found that one night of no sleep reduced muscle growth by 18%. Sleeping less than 8 hours before a workout will also cause you to be 1.7 times more likely to pull a muscle. On the other hand, getting only an hour more sleep will decrease your odds of injury by 70%.

When to power through and stick to that morning workout:

If you had one random night of bad sleep, it might be best to drag yourself to the gym that morning. You’ll even see some unexpected benefits! A morning workout will give your tired brain a much-needed lift. A study from the University of Georgia found that exhausted participants who participated in a 10-minute morning workout saw a boost in alertness more powerful than 50mgs of caffeine.

However, research has found that there are certain guidelines you should follow to ensure that your sleepless workout is still beneficial to your body. When doing a morning workout on a bad night of sleep, you should consider the type of workout you do and what time of day you work out.

The type of workout you do after a bad night of sleep can impact the effect on your body. One study conducted by a team of Australian researchers examined how a sleep-deprived body is impacted by different kinds of workouts. The team compared strength and endurance workouts to workouts that require complex skills, like archery or tennis. The results demonstrated that poor sleep decreases complex skills by as much as 23%, while endurance and strength declined by only 5-8%. This means that going for a run or lifting weights should be fine after a night of bad sleep, but you might want to avoid a game of tennis or volleyball.

The time of day you work out after too little sleep also matters. If you hop out of bed and book it to the gym, the effects of sleep loss will actually be minimized. The researchers found that athletic performance of complex skills dropped by 16% if the workout was done in the morning, but by 25% if the workout was done in the evening. Similarly, tired participants who lifted weights in the morning performed 2% worse, whereas evening exercisers performed 5% worse.

The researchers also found that the detrimental effects of working out while tired are stronger among exercisers who lost sleep by getting up too early compared to those who went to sleep too late. So, waking up at 4am to squeeze in a workout before a trip to the airport might not be the best idea.

This athletic performance decline throughout the day is likely related to the body’s circadian rhythm. When we wake up in the morning, our body releases adrenaline at the sight of morning light. Moreover, a chemical called adenosine increases in quantity as the day goes on. The more adenosine in your body, the more tired you’ll feel and the harder it will be to get a good workout.

The bottom line:

The choice of whether to wake up and work out or catch a few more hours of sleep after a rough night is ultimately in your hands. When making this decision, it’s important to consider several things:

  • How many nights in a row you’ve been missing out on good sleep

  • What kind of workout you do

  • What time of day you choose to workout

  • Your stress level

  • Whether or not you’re trying to build muscle

Our recommendation is to take it easy if you’ve been pushing yourself hard lately and listen to your body. Your body will tell you if it wants to work out in the morning or get some more hours of sleep. So listen up!


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