The simple way to figure out when you're most productive, according to Google's executive productivity advisor

• Google's Laura Mae Martin advises executives on identifying their most productive hours.
• Martin detailed her method in a new book.

Not all hours of the day are created equal, according to Google's executive productivity advisor, Laura Mae Martin.

Her job is narrowing down the most productive times for some of Google's top leaders, and her method is surprisingly pretty simple.

In her book, "Uptime: A Practical Guide to Personal Productivity and Wellbeing," Martin said that each person has different high and low energy periods.

"Some people are night owls and some people can function well at 5:00 a.m.," she said. "It's built into our systems."

To uncover these internal clocks, the first question she asks executives in her coaching sessions is: "If you had an entire day tomorrow, with no meetings, no interruptions, no standing commitments, but a bunch of things to get done, how would you structure your day?"

Their answers varied drastically. Some clients preferred working into the evening after late lunches, while others liked starting at dawn with an afternoon break or workout.

But everyone has their "power hours," which Martin describes as "the two to three hours a day that you feel your most productive."

Martin suggests keeping a little notepad by your desk for two weeks and writing down any time you feel particularly productive or have low energy.

"Once you've come up with some of your general productivity patterns, you can start mimicking your ideal conditions as often as possible," she said.

Ideally, Martin said these power hours would be spent on tasks related to your top three priorities. If they partially overlap with other fixed commitments like mandatory meetings, Martin recommends blocking your power hours to whatever degree possible.

"Even one to three times a week, or even just one hour of your three Power Hours, will make a huge difference in how much control you feel over your work and to-do lists," she said.

Martin said that multiple clients have told her that "this one single shift in their schedule has made the biggest difference in their overall productivity." In one case, an executive used to take her lunch break at noon every day before realizing that it fell right in the middle of when she felt most productive.

"She started taking a later lunch and found that the 12:00-1:00 p.m. hour was one of her most productive hours each day — and to think she used to spend it eating lunch!" she said.

That doesn't mean you're confined to only working during those high-energy hours. What Martin calls "off-peak Hours" are great for other activities like quick emails or coffee chats. They can also actually be optimal for more creative undertakings.

She cited research by Mareike Wieth, a professor of psychology at Albion College, which indicated that people tend to be more creative when they are less focused and more open to a broader range of information.

Martin said that knowing your power and off-peak hours helps you maintain control and produces better output. It also "gives you the permission" to have times of low energy in the day and utilize them for more compatible tasks rather than burning yourself out.

"The best way to think of this is: When am I in the mood to do this type of task?" she said. "Slot it there!"