Sunday, September 24, 2023

Does Exercising At Night Lead To Sleep Problems?

Mild or moderate intensity exercises are good before sleep time but avoid intense or heavy workouts as they can hamper sleep quality.

Let me confess that I am biased; I have been exercising late evenings for more than thirty years—running, weight training, cycling, and even rowing (in the gym). Some of these have been tough workouts—more than five hundred (yes, you read that right) of my half marathon or longer runs have been after sunset. And they have rarely worsened my sleep.

But what does the science say? In this article, we look at the evidence on both sides of the debate.

Why You Should Not Exercise At Night

There are multiple reasons why experts say that you should avoid exercising late evening or at night.

Exercise and Core Temperature

The main objection against late evening or night exercise is it increases your core temperature—the one that of your organs deep inside your body such as the liver or intestines.

This temperature is controlled by your body between 36°C and 37°C throughout the day. Two hours before you get ready to sleep, this temperature starts falling slowly.

When you exercise, the core temperature can rise to even 40°C, which revs your body and tells it: Don’t sleep. That is why experts advise not to exercise in the night.

More recently, that theory has been debunked. The scientists now advise that you should avoid exercising in the two-hour window before sleep and keep your evening exercises to light or moderate intensity.

Exercise and Stress Hormones

Exercises increase adrenaline, a stress hormone. When higher levels of adrenaline are coursing through your blood, it is difficult to fall asleep.

Mild or moderate exercises do not increase adrenaline levels significantly after exercise. So once again, mild and moderate exercises are okay in the evening or at night.

On the other hand, adrenaline does not get cleared from your blood properly during exercise and after a very strenuous exercise, adrenaline levels can stay high for as long as 48 hours.

Cortisol is another stress hormone secreted during exercise. Normally, its blood levels rise as you wake up, peak within 30 minutes of your being awake, and slowly drift down through the day, dipping very low at night. Elevated levels of cortisol can lead to sleeplessness.

High-intensity exercises increase cortisol levels.

Interestingly, low-intensity exercises don’t increase cortisol but rather reduce its levels, helping in better sleep.

Exercise and Safety

Exercising at night is less safe if it is an outdoor activity such as running. This is especially true for women. Consider running in a group at night.

Exercise and Ambient Light

If you exercise in a gym that is bathed in white LED lights, it will affect melatonin secretion. Consequently, you will find it difficult to sleep for at least a couple of hours after finishing.

Exercise and Food

If you exercise at night, it is difficult to have dinner before working out.

If you have dinner after you finish it, you will feel full going into your sleep time.

In general, one is advised to have the last meal of the day at least four hours before bedtime. You may consider skipping dinner or having something really light before and after the workout.

Now let us look at reasons why exercising at night can help.

Why You Should Exercise At Night

I did not mean to say that you should avoid exercise during the day and switch to nighttime. But the caption looks good in contrast to the earlier one; so I will let it be.

Yet, there are some situations where nighttime exercise can actually help improve sleep.

Exercise and Anxiety

You must have noticed that if you do any high-intensity exercise, it is difficult to focus on anything other than the workout. It is tough to mull over your worries during that period, leading to a better mindset at the end of the workout. I have noticed this anxiety-reducing effect very clearly but only with a strenuous workout.

On the other hand, a light workout will reduce cortisol levels, reducing anxiety.

Exercise and Better Sleep

A survey found that people who exercise after 8 p.m. fall asleep quickly, sleep deeply, and wake up well-rested.

Besides these, exercise done at any time of the day has many benefits for sleep such as reducing symptoms of insomnia, daytime sleepiness, and obstructive sleep apnoea. In some people, exercise has been found to reduce the need for sleep medicines.

By the way, the old belief was that exercise releases endorphins, which get you into a highly joyous mental state post-exercise. Recent studies have shown it to be a myth: endorphins can’t cross the blood-brain barrier to reach your brain. If you feel euphoric, it is for a different reason. But all these points need a separate article to discuss.


  • Light or moderate-intensity exercises are great before sleep time.
  • End your workout at least two hours before bedtime, though even one hour gap has been found to be fine.
  • Avoid rigorous exercises at night.
  • It is better to exercise at night than not exercise at all. For many people like me, who cannot exercise in the morning for personal reasons, nighttime is the only option.
  • Exercise is best performed as a habit and you are likely to continue with it, only if the timing is consistently suitable. So the best time to work out is the one you can regularly adhere to.

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First Published on: 5th July 2023
Image Credit: Image by Freepik


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