It seems a given that most people want to increase the amount of exercise they have each day and increase how much they sleep each night (or at least the quality of sleep they have). But do these two desires, exercise and sleep, work against each other? And if so, how can we fit one into our day without it adversely affecting the other? There are a lot of common myths about the relationship between exercise and sleep. In this article, we will tackle them head-on.
First, let’s talk about what we know about our current need for exercise and sleep. The importance of sleep is well-documented.
- The Centers for Disease Control and Prevention1 estimates almost one-third of adults get less than the recommended seven hours per night.
- When it comes to teenagers, two-thirds report sleeping less than the recommended eight hours on school nights.
- Combine these lackluster numbers with the fact that one-half of adults do not meet the minimum federal Physical Activity Guidelines2.
This is not to say that lack of exercise and lack of sleep are directly related, but if these are both areas of your life you’d like to improve, read on to understand the role they play together.
Traditional Understanding of Exercise and Sleep
The general consensus advised against exercising in the evening, as it would have a negative effect on sleep. It seemed more natural to promote exercising early in the morning, as a boost to your day. And the rituals or habits we do at night, often referred to as our sleep hygiene, can have a significant impact on our quality of sleep.
Exercising in the evening brought concerns of stimulating your body as you were trying to wind down. If you ran for five miles in the evening, the idea was the elevated heart-rate, the increased amount of oxygen to the blood, would give you a boost of energy that would lead to an increase in sleep onset latency (the amount of time it takes to fall asleep after your lights are off and your head hits the pillow).
However, several studies are showing the matter isn’t so simple. Before we go into why we are going to talk about the two types of exercise and their effect on our bodies.
What Exercise Does to the Body
Aerobic exercise is often referred to as cardio. In fact, the word means “with oxygen” because it requires increased pumping of oxygenated blood to the heart. During aerobic exercise, you will be sustaining an increased heart rate and breathing rate. These are activities such as running, swimming, and hiking.
Maintaining a weekly schedule of consistent aerobic exercise is often linked to having a lower risk of depression, osteoporosis, diabetes, cardiovascular disease and more3.
Anaerobic exercise is an exercise which is intense enough to cause lactate to form. The word itself means “without oxygen.” This type of exercise is best understood through the visual of weight-lifting: someone straining to lift heavy objects and doing it slowly and methodically. Anaerobic workouts build muscle mass. While a jog or run is aerobic, a sprint (running at max capacity for a short distance) is anaerobic, because now you are exerting more energy than you are taking in oxygen.
Anaerobic exercise occurs, as Healthline reports when we prompt our “bod[ies] to demand more energy than [our] aerobic system can produce.” This makes our body use energy stored in our muscles.
The benefits of anaerobic exercise are varied, from increasing metabolism to reducing the risk of disease4.
New Understanding of Exercise and Sleep
As we mentioned above, the research and common-sense thinking showed evidence of avoiding exercising in the second half of the day. However, there is now evidence that shows exercise has either no effect on sleep onset latency or a positive effect.
A study from Northwestern Medicine focused on the effects of aerobic exercise on middle-aged or older adults who were suffering from insomnia. The study was looking at the effects of non-prescribed solutions to insomnia. When the group of participants engaged in aerobic exercise for “two 20-minute sessions four times per week or one 30-to-40-minute session four times per week” for 16 weeks they reported an improvement in sleep quality, less depressive symptoms and more energy throughout the day5.
A new study, published in December 2018 in Sports Medicine, showed no negative change in sleep habits when participants exercised within 4 hours of going to bed. However, there was a negative change if a participant exercised within 1 hour before bedtime 6.
While these are not hard-fast rules, the evidence is now supporting the idea that evening exercise can benefit your nightly sleep routine. Whether you choose to start exercising later in the night or not, we recommend you keep in mind these general guidelines for better sleep: try to create consistency in your nightly ritual, do not exercise, neither aerobically or anaerobically, an hour before bedtime, and keep a sleep journal nearby to document how you feel the morning you wake up, whether you are ready to start the day or have a strong urge to keep sleeping in.
- 1 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5385214/#B2
- 2 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5385214/#B8
- 3 https://www.medicinenet.com/aerobic_exercise/article.htm#aerobic_exercise_facts
- 4 https://www.healthline.com/health/fitness-exercise/anaerobic-exercise#1
- 5 https://www.sciencedaily.com/releases/2010/09/100915140336.htm
- 6 https://link.springer.com/article/10.1007%2Fs40279-018-1015-0