There are a lot of things to consider when you’re choosing the optimal time to train. Chiefly among them is when are you physically able to. Are classes or gym time available to you when you’d ideally train? What’s “ideal” anyway? 

These are all great questions, but if you’re looking to maximize your results, it pays to examine this issue a bit more. What follows is about a decades worth of observation and summary of increasing research to interpret and draw conclusions from.

I used to debate this topic with my colleagues years ago as we had downtime in the gym. We’d often be at the gym at 4AM to train with clients who booked to train with us at 5AM. Sometimes, we’d be unlucky enough to have to stay at the gym to do a 7PM session that night. Those were some long days. Obviously, not ideal for us. But it got us thinking: beyond schedule dictating your training time, is it even a good idea to be training at the fringes? What is the ideal training time anyway if there even is one?

As the years went on and I learned more about the human body and performance, a few things emerged that really led me to believe that for most individuals to straddle the line of health and optimal performance, their training should not render them unable to sleep by 11PM. At that point, you’re simply robbing yourself of sleep and you have to ask yourself what you’re trying to achieve and if there’s a better way to do it.

If I had to put it simply, you should strive to train between the hours of 6am and 4pm. Some athletes and others can take some liberties based on availability, provided that they are not experiencing adverse sleep effects from their training schedule.

Why do I take that position? Let’s explore below…

Cortisol “Curve”

Cortisol itself is a stress/adrenal hormone that chiefly plays a role in how you metabolize energy when you’re in heightened states or a “fight or flight” style responses. Cortisol is typically “fired” and elevated during a workout in healthy individuals, as it helps signal glucose utilization to fuel its efforts. It’s how your body communicates to itself how to keep you slugging, moving and lifting.

Cortisol also serves a very important role in helping wake us up in the morning hours and keeping us in a normal circadian rhythm. Below you can see what a normal cortisol level looks like over a 24 hour period:

As you can see in the morning hours, cortisol levels are at their highest naturally and start to decrease sharply after noon.  That is to say it’s a diurnal hormone (daytime)— it should not be present in the late evening hours.  In some individuals who have sleep issues, cortisol levels can be high at inappropriate times.

How it Relates to Training

You may have started to realize it, but if cortisol is essential during training, you’ll inevitably have elevated levels of it, regardless of the time of day you train. However, for this reason, working out too late in the evening may not be the best use of time for the reason that you’re likely to spike the levels way too high to hope to “come down” before its bed time, especially if you have issues sleeping and relaxing post-training.

I’ve seen a few issues arise in individuals who workout too late in the evening. To be very clear not everyone will experience this by any stretch. However, the individuals in question would have a really difficult time having restful sleep or even getting to sleep at all if they weren’t done with their workouts before 7pm.

The key here is “restful sleep.” In many cases, you want to already be experiencing or approaching your most deep sleep by midnight for optimal growth hormone balance. You may be able to train late, and get home and sleep quickly, but the quality of your sleep should come into question.

I’ve also had clients report to me that if they perform any endurance or cardio work too late in the day, sleep is almost always futile. This makes sense, as cardio can be a particular cortisol “dump” in terms of exercise. 

To illustrate/contrast visually: the chart above roughly outlines what a normal cortisol curve looks like (blue line), overlaid with someone who may be having an inverse curve (red line). The red line may be someone who trains too late in the evening and is forced to stay up late in order to “come down” before they can sleep.

Modern Sleep Study and Profiles

Modern sleep studies and profiles of individuals have found that there is genetic precedence for an individual’s ability to fall asleep before or after certain times. Some people are truly “night owls.” Lost in that discussion from the lens of training and fitness however, is what we can do to make sure that your needs are met on the sleep/recovery ends of the spectrum if you’re one of those individuals.  

I always get people asking me, “What about people like _____?” I think you can probably guess some names I hear. They’re the ones who brag about their lack of sleep and high output. There are many.

That’s great, in fact, I love those people. But if you’re experiencing poor results and you already train to the extremes— you’re not them. Especially if you aren’t healthy already. If your goal is health or performance, those aren’t habits to emulate. Emulate the attitude and no bullshit/excuses mantra? Yes.  Trying to fit more in at the expense of messing up your sleep? No. 

What I would do in the case of these “night owls” is ensure they do not have to be up too early in the morning. You have to give a little to get a little. Those who train late and get to bed post 11PM should ensure they aren’t up before 7-8am. Otherwise, you’re simply robbing yourself of sleep. Whatever it is you hope to get from your training will be hindered by the lack of recovery.

It’s also worth mentioning that reseting your circadian rhythm is possible. There are a great deal of resources out there, including professionals who can help you modify your behavior in an effort to help you develop better sleep hygiene. Look into CBT Therapists in your area that specialize in insomnia.

The Reverse Problem: “Don’t step over dollars to pick up nickels.”

The issue with working out too early in the morning if you’re not adapted to it (or if you’re staying up too late to train)— is that you may be actually getting in your own way. Stan Efferding always said “Don’t step over dollars to pick up nickels” as it relates to your training. In other words, you may be robbing yourself of far more by training until 11PM than you’re gaining (or waking at 4AM to do cardio).

To be in the gym at 5 or 6am would mean you’re likely waking up around the 4am hour. Most individuals who aren’t used to this will be incredibly groggy, unable to eat, and find themselves too “asleep at the wheel” to perform that early.

The operating word there is “individuals who aren’t used to this.” That is to say, you can most certainly condition yourself to train that early. If I had to pick a timeframe (ie: early morning or late night) that was most worth training your body to adapt; it would be early morning.

Still however, I understand, there will be cases where this is contraindicated, for many of the above reasons.

So when is the best time to train?

The optimal time will be dictated by all the above factors. If you’re able to control your sleep and have no sleep disturbances, I would ideally recommend between 6am and 4pm. I recognize that the individuals who want to train before 5am or after 8pm are usually doing so because they have no other choice. In this case, I would say you need to be extra diligent in managing your sleep, stress levels and eating habits outside of training.

In summary, think of the below like your “Cheat Sheet” in figuring out your optimal training time:

Answer the following questions:

1. What times am I physically available to train? (ask yourself some hard questions— can I really make time if I tried harder?)

2. How is my sleep hygiene?

   • If it’s healthy, you can take some liberties in the time you train so long as you keep up these good sleep habits.

   • If it’s poor, work on this first, and schedule accordingly.

3. Am I otherwise healthy in a general sense?

   • If so, think of times when you’re feeling best physically in general.

   • If you’re not healthy and working on other physical health related issues, strive to workout and train between the hours of 6am and 4PM. This will keep your cortisol levels in check and aid in your sleep hygiene.

While there’s definitely room to push boundaries, I do feel comfortable in saying that minding the above will give you the best chances of success in your training.