By doing difficult or important work in your peak energy window, you can greatly increase your productivity and the quality of your work. Here is how to find out when your peak energy window is.

Have you ever been asked, “Are you a morning person or an evening person?” If so, what did you answer?

While this is a useful question in order to get to know yourself better, the truth is more nuanced than that. Till Roennenberg, author of Internal Time, developed a useful way to think about this. With a couple of simple steps, you can figure out for yourself when your peak energy window is.

Let’s say you’re on vacation; you don’t have to wake up early for work, and you also didn’t stay up too late last night. You went to bed when you got sleepy, and you woke up rested.

On that morning, at what time did you wake up? That is your natural wake up time.

After you’ve naturally woken up, the body has some sleep inertia which lasts for 2-3 hours. Once the sleep inertia has receded, your peak energy window starts and lasts for about 4 hours. To illustrate this, let’s take an example:

Natural wake up time: 8:00
Sleep inertia: 8:00-10:30
Peak energy: 10:30-14:30

In order to take advantage of your peak energy, you should work on the most important task for the day (or the most difficult thing for the day) in that peak energy window. Other tasks, such as email and administrative tasks, can be left for other parts of the day.

So if your natural wake up time is around 8:00 and you start work at 9:00, you’ll be trying to work in the middle of your sleep inertia. It’s not surprising, then, that you can’t get yourself to focus or be productive. You’d be better off doing some simpler tasks until about 10:30 and then starting on the important/difficult task.

You may have noted that lunch falls right in the middle of that peak energy window for most of us. This could be a bit of a waste since many of us experience an after-lunch dip. To minimize it, you may eat a medium-sized lunch instead of a big one since a smaller meal will make you less sleepy. Also, metabolizing carbs tends to make us more sleepy than metabolizing protein or healthy fats, so you may want to minimize carbs at lunch and include more at dinner, for instance.

If you’ve seen my previous blog post about swallowing the frog first thing in the morning, you may be confused: these two blog posts seem to give conflicting pieces of advice. This may very well be the case, and you need to figure out what works best for you. That’s why it’s best to try out both and see how you feel and perform with each.

For someone with an early natural wake up time, doing the important task first thing in the morning may be effective since it coincides with her peak energy window. For someone with a later natural wake up time, however, this would mean trying to work on something difficult during their sleep inertia period, which may not be a great idea.

My natural wake up time is early, so my peak energy window is approximately 9:00-13:00. Often I actually move my lunch to 13:00, so I’ve used all my peak energy time for focused work. In the afternoon, I can focus, but it’s more difficult (unless I have some green or black (!) tea). After 17:00, don’t count on me to concentrate well.

In contrast, I know people who are only really awake from 14:00. A colleague of mine knows this about himself and has purposefully switched his working hours to 12:00-20:00. He does his best work 14:00-18:00. He used to try to work in the mornings, but he ended up not delivering results because half of his days were wasted.

This is why it’s important to figure out when you do your best work and, if you have the possibility, try to adapt your schedule to that. I realize that not everybody has such a flexible schedule, but for those of us who do, it’s a shame not to use such a simple tool.

What is your natural wake up time? Do you experience sleep inertia? When is your peak energy window? Are you able to focus in the afternoon/evening? I’m really curious, so please let me know! Comment below or on Facebook, Twitter, or LinkedIn.