Productivity Self Improvement

Discover Your Most Productive Hours with This Simple Method

Rob Nightingale 24-02-2016

In his book Work the System, Sam Carpenter coined the term “Biological Prime Time”. This bombastic term means little more than “your most productive, focused time of day”.


In this article you’ll be given an incredibly simple Excel spreadsheet to help you calculate your own “Biological Prime Time”. This will help you to understand when you work best, so you can structure your day efficiently around these periods of productive time.

Understanding Your Prime Time

Each one of us has an ultradian rhythm. This is a recurrent cycle that our bodies go through each day. This pattern was first noticed by sleep researcher Nathaniel Kleitman, which caused a mountain of research to be conducted in this area.

The results of this research clearly show that the human body goes through cycles of between 90 and 120 minutes. Through each of these cycles we are taken from an unproductive trough, to a productive peak, and then back again.

This much we can take as true. But from personal experience, it’s obvious that these peaks and troughs are far from equal.

Some troughs leave us prone to distraction and procrastination How Procrastination Changed the World We often think of procrastination as an unnecessary hindrance to our everyday lives. But if it weren't for procrastination, the world would be an entirely different place. Read More . Others leave us aching for bed. On the other hand, some peaks see us happy to work through a few emails. Others leave us in a state of deep focus and creativity How to Regain Creative Motivation After You've Burned Out Writers aren't the only ones who suffer from "creative block". What can you do to rekindle your creative fire? Here are five easy things you can try. Read More (a state of Flow as psychologists like to call it).


Wouldn’t it be handy if you knew exactly which of your ultradian peaks tended to be those you could rely on to get your best work done?

Calculating Your Prime Time

Once you have used the following spreadsheet to calculate your most productive time of day (those ultradian peaks that peak higher than the rest), you should aim to use that time especially carefully.

This is the time of day that you will be at your most focused, and most creative. This is when you’ll be able to produce your best work. So tackle the less demanding tasks outside your prime time, while during your prime time, remove distractions and concentrate on your most important work.

Points to Note

Before we get into the meat and potatoes of tracking your prime time, you should keep the following in mind.


Using The Spreadsheet

The spreadsheet we’re going to use to track your prime time is inspired by the one used by Chris Bailey in which he tracked Energy, Focus, and Motivation. Unfortunately, he didn’t share the spreadsheet he created, so I’ve created and shared one for you, which also tracks Creativity.

You can track more variables (or rename the variables in the spreadsheet) if you wish, but be prepared to track each of these variables during every waking hour. Don’t make it too daunting for yourself.

First of all, you can download the Prime Time Calculator Spreadsheet I’ve created here (Excel). Feel free to create your own if you’d like additional functionality, or if you want to use the spreadsheet in another program.

Alternatively, you could use apps like TogglLoggr, or Track & Share to track this information, too.


Peak Productivity Calculator

Using the spreadsheet should be fairly intuitive. From the moment you either wake up, or start working (it’s up to you), start tracking your Energy, Focus, Motivation, and Creativity on the hour, every hour. Set an alarm to remind yourself to do this. It should only take around 20–30 seconds per hour.

If you decide to only track from 9am, you can leave the entries before 9am blank. The same goes if you stop tracking at 5pm. That being said, do try to only track during the same times each day, otherwise the data could be skewed.

All you have to do is score how you’re feeling in each area out of 10. Be completely honest with yourself here, and don’t fall victim to the Hawthorne Effect where you may feel tempted to increase your scores just to make yourself feel better.


As you start inputting data, you’ll see the Totals and Average column will fill automatically. As will their respective tables and graphs on the right hand side. You don’t need to touch these.

Totals and Average Results

If you wish to track just 5 days instead of 7, you will have to change the formula in the Average column to divide by 5, instead of 7.

Understanding Your Data

This spreadsheet will only track the absolute basics needed to understand your most productive times. This makes it easier to understand the data without getting into rocket science. Even after just two days, I could start to see patterns in my productivity cycles.

Biological Prime Time Spreadsheet

From waking up between 7am and 8am, my energy levels quickly spiked, gradually dipping between 11am and 1pm. At around 3pm those levels peaked again for a couple of hours (perhaps the energy from my lunch kicks in around then), before giving in after 5pm.

Obviously, the longer you track your productivity, the more reliable your insights will be.

Taking Things Further

Once you’ve figured out your current peak times, you would want to take things further. Before you do this though, be sure to carefully review the data you’ve collected The Quantified Self: How To Track Your Life With Your iPhone If you track your actions, you will be able to do them better. However, tracking can be tiresome if you don't have the right tools. Let's make it as simple as possible. Read More so far.

Math Equations

If, as recommended earlier, you kept a daily journal, you should look out for any obvious patterns. Perhaps a bad night’s sleep affects your productivity more than you think. Maybe your productivity crashes after a long meeting. Maybe your peak productivity happens when you’re out of the office.

Similarly, you could use an app such as Moves (iOS, Android), which automatically records things such as steps taken and location. These data points are recorded without any input needed from yourself, so it’s an incredibly easy way to gather some additional data to play around with.

Any insights you garner from your data will reveal how your productivity levels change based on time of day, routines, etc. Once you have this insight, try tracking your productivity again after making one change (try to only change one variable at a time so you can more accurately measure its impact on your productivity). As a few examples:

The variables you choose to alter are countless. Have fun with it!

Start Your Life Experiment

Calculate your Productivity

Download the Prime Time Calculator Spreadsheet here (if you don’t want to scroll up).

Track your own productivity for a few weeks to find your own periods of peak productivity; that is the first step to organize your days around your energy.

Please leave a comment to let us know what you learn from tracking your productivity. And if you’d like any extra functionality added to the spreadsheet, let me know, and I should get around to updating the spreadsheet in due course.

Image Credits: cheerful businessman by ra2studio via Shutterstock, Mathematics *Explore April 24, 2013 #4* (at one time) by Tom Brown (Flickr)

Related topics: Habits, Productivity, Time Management.

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  1. Andréia
    January 27, 2017 at 7:39 pm

    How did you measure your creativity?

    • Rob Nightingale
      February 27, 2017 at 9:18 am

      Nothing impressive, I'm afraid... basically just how I "felt" during tracking.

  2. Kushang Agrawal
    September 6, 2016 at 4:22 am

    I couldn't find the download link.
    Could you please help?

  3. Ben
    March 4, 2016 at 11:39 am

    How do we add additional weeks? It only has 1 week right now.

  4. Noukka
    March 3, 2016 at 2:59 pm

    Oh this would be really interesting! I wish the sheet would track up to 11:00pm. I'm not sure if it's easy for me to change that?

    • Rob Nightingale
      March 3, 2016 at 3:21 pm

      The sheet is completely customizable, Noukka. You just need to add more rows underneath the current rows. You can find my email on my profile page if you would like me to walk this through with you in detail.

      • Noukka
        March 3, 2016 at 3:44 pm

        I'll see if I can work it out first, I'm not too familiar with Excel but would like to be. I might need some help with getting the graph working, so I might get in touch then. Thank you!