Here’s how swimming twice a week affected my sleep

I enjoy being in and around water, whether it’s a pool, lake or ocean. The house I grew up in is right across the street from the swimming pool in my hometown. It goes without saying that most summers were spent in the water, from playing with friends and taking swimming lessons to becoming a swim instructor, lifeguard and competitive swimmer.

It turns out that this enjoyment of water is also backed by science. You may have heard of a “blue recipe” or the blue mind theory, popularized by marine biologist Wallace Nichols. These theories suggest that there are intrinsic beneficial connections between humans and water. Being around water or “blue space” has been shown to increase dopamine, serotonin and oxytocin in the brain and decrease cortisol levels, which lowers heart rate and stress levels.

Initial thoughts and expectations

For this experiment, I wanted to investigate the impact of swimming and being around water on my sleep quality. Unfortunately, I don’t live near an easily accessible natural body of water like a lake or ocean. However, I live near an indoor pool, where I decided to swim laps.

I dove headfirst into this research, assuming for some reason that I would sleep better on the days I swam. Not only does being around water have a naturally calming and meditative effect, but swimming is also an excellent form of exercise and has many known benefits, including better sleep.

I spoke with licensed psychotherapist and sleep specialist Annie Miller, who explained that movement and exercise increase the body’s natural sleep drive, allowing us to feel more sleepy and have better quality sleep in general, and swimming is no exception.

“Swimming is an activity that promotes deeper, more conscious breathing, which encourages relaxation. Deep breathing can positively affect sleep quality,” said Annie.

Let’s be clear: I’m no scientist, but I’ve done my best to keep all other variables equal. I limited my coffee consumption to two cups in the morning and kept my diet similar every day, including what and when I ate. I didn’t drink alcohol and took the same jelly beans to sleep every night. I also didn’t engage in any other form of strenuous exercise on the days I wasn’t swimming.

I swam a consistent distance of 1 mile each swim day. The only difference was the speed at which I completed the mile, which ranged from 38 to 40 minutes. I tracked my workouts and sleep data on my Apple Watch and waited until the end of the tests to compare and contrast the information to avoid prematurely influencing the results. Right away, though, I noticed that my sleep quality seemed worse on the nights after I swam than on the days I didn’t swim.

Swimming and sleep data

the results

The final results of this experiment surprised me: on average, I actually slept less and was more awake on swim days compared to non-swim days, essentially the opposite of what I expected to find.

Sleeping on bath days versus no bath days

I also noticed an interesting pattern with my sleep when comparing swim days to days off immediately following a swim day, or what I’ll call a “recovery day.” On swim days, my total sleep time averaged just under 7 hours, and my awake time was about an hour per night. On recovery days, my total sleep time was much higher: about 8.5 hours, with a significantly shorter wake time of about 30 minutes.

Sleeping on swim days versus recovery days

To be honest, I was baffled. I have read online to see if others have had a similar experience and found the likely cause. According to writer and competitive swimmer Olivier Poirier-Leroy, the more intense the workout, the more difficult it can be to sleep due to elevated levels of cortisol and norepinephrine (adrenaline). In fact, it can take up to 48 hours for norepinephrine levels to return to normal after high-intensity exercise, which seemed to be the case for me.

Constantly walking out of the swim center with wobbly pool noodle legs was probably a sign that I was pushing myself a little too hard. Despite not having the results I expected (or hoped for), I noticed some other interesting changes during this experiment that are harder to quantify but worth mentioning.

My stress disappeared

My lap swim sessions occurred in the middle of my work day, around 1pm. Every time I left for the swim center, I felt sluggish and stressed about going there when I had other tasks to complete. Some days, I even had an accompanying tension headache before the swim and was generally not in the mood to do the workout.

During training, these negative feelings would gradually fade away. I started out wanting to get into that meditative state where I could just focus on breathing and quieting my mind.

After each bath, I noticed a significant improvement in my mood. I was less stressed and didn’t experience the typical afternoon slump when I would normally opt for another cup of coffee to get me through the rest of the day. I felt physically tired, but mentally energized and focused, ready to tackle the rest of the day’s to-do list.

Conclusion and final thoughts

I think being in and around the water had positive calming effects, as the blue mind theory suggests, but perhaps not enough to overcome the cortisol levels I was experiencing from overexerting myself.

As Dory from Finding Nemo says, I’ll “keep swimming” using the insight gained from this experiment until I find a happy medium that improves my sleep quality. I hope to conduct similar studies with less intense workouts or simply spending time near the water every day to explore these theories further.

If you’re like me and you’re looking for ways to get better rest, stay awake with our simpler tips and tricks, such as limiting your technology use, developing a bedtime routine, journaling or meditating, and taking me — Make sure you exercise at the right intensity level and at the right time of day.