We’ve talked before about how smart time management is essential to staying productive. With your day organized to make room for all the tasks you have to do, you can make the most of the 24 hours you have in a day.

But ultimately, no matter how good your time management is, you still have a finite amount of time available to you. Those 24 hours you have each day, no matter how well you organize them, will not increase. Time-Turners that let you freely add hours to your day unfortunately only exist in the world of Harry Potter (and only for Hermione, so that she can get to all her classes on time).

However, what you can do is increase your energy. This is where energy management comes in.

“While there may only be 24 hours in a day, your capacity for energy isn’t a fixed quantity.” - Scott Young

Energy management has long fascinated productivity experts. Used in combination with good time management, it helps you get the most out of your day by identifying your body’s peak productivity times and adjusting your work accordingly. It’s an important component of your overall task management.

Tony Schwartz, performance expert and CEO of The Energy Project, is among many who have realized that our current way of working isn’t really working. For a long time, the conventional thinking has been that to be successful, you need to work longer, push yourself harder, and sacrifice other parts of your life to focus on one goal.

Schwartz found that simply attempting to increase your output actually hurts productivity. To work at your absolute best, your mind and body need real restoration and rejuvenation. Pushing yourself harder prevents you from getting this much-needed rest and will eventually cause burnout, decreased concentration, and will take a toll on your job performance.

If we start our working day knowing that we won’t take a real break until the day is over, the result is that we will try to preserve our energy and distribute our efforts at 25% across the day. This prevents us from both reaching our full productivity and from taking a restorative break.

Instead, what we should be doing according to Schwartz is using 90% of our effort at moments that correspond to our body’s natural productive rhythms. These moments when we’re at our most alert and most focused are when we get our best work done. When our energy hits a slump, instead of powering through it, we should instead take a break or switch to tasks that require lower concentration. Switching up low-energy moments with “hold nothing back” periods at work is what Schwartz sees as the key to productivity.

So what’s the science behind it?

Peretz Lavie, renowned psychophysiologist and author of several books, found that our energy works according to ultradian rhythms, a natural cycle of high and low energy that takes place throughout the day.

To get an understanding of these cycles, he conducted a series of experiments on several young adults where he put them on ultrashort sleep schedules: for an 8 hour period, he would have them spend 15 minutes awake, then 5 minutes sleeping. Then repeat.

Of course, test subjects couldn’t fall asleep for 5 minutes every 15 minutes. So what Lavie did was he analyzed when they could and couldn’t fall asleep.

What he found was that many young adults were alert for most of the afternoon and evening, only hitting energy slumps at around 4:30 PM and 11:30 PM. In the morning, however, they got sleepy every 90 minutes.

tumblr_mc44uswExD1qhg0wtThese 90 minute cycles are our “ultradian rhythms.” They define when we feel naturally awake and productive, and in-between we have 15-20 minute periods where we feel drowsy. Our best performance occurs in the 90 minutes between periods of drowsiness. Many professionals have recognized the value of adapting their work schedule to their ultradian rhythms.

Ultradian rhythms in practice: pilots and violinists

Contrary to popular belief, it’s not necessarily the musicians who practice the most or the professionals who work the longest who are the most successful. Of course, pushing yourself is necessary - practice is the only way you get better - but it’s not beneficial if you do it at moments of low energy.

Anders Ericsson researched the habits and performance of world-class violinists and found that the very best among them did not in fact spend more time practicing. Instead, the time during which they practiced was one where they had a more deliberate focus. On average, they practiced for four and a half hours a day, in 90 minute intervals. Working with their ultradian rhythms instead of against them, they performed better. On top of that, they also got more sleep than their peers.

The benefit of following the human body’s natural ultradian rhythms is one that is clearly seen with airline pilots. In 2008, the Federal Aviation Administration conducted a study which found that short breaks between long work sessions resulted in a 16% improvement in focus and awareness. Pilots who didn’t take a break had a 35% deterioration in reaction time at the flight’s halfway point. Also, many fell asleep on the job as a consequence of fatigue: 80% of regional pilots say they’ve accidentally taken a micro-sleep during a flight.

Your brain is a muscle: treat it like one

An athlete training for a marathon knows that he has to build up his stamina gradually, pushing himself to run for longer and longer periods throughout his training. He also knows that he has to let his body recover in-between training sessions.

We need to do the same with our brain. None of us have infinite creative and productive energy; like our arms, legs, or abs that get tired after a workout, our brain also needs to recharge in between bursts of productivity. By setting periodic goals, we can gradually increase our energy capacity. Whether these goals are daily, weekly, or monthly, we can learn to work hard during moments of high energy and properly recuperate during moments of low energy.

Oscillating between harder work and lighter work builds up our capacity and teaches us to manage our energy efficiently. This is perhaps the most important part: even if we have a large capacity of energy available to us, it can be an easy thing to waste if not managed efficiently. Moments of high energy need to be combined with productive tasks for us to get things done.

Energy management is crucial to our wellbeing and our professional success. Here are our 3 tips to perfect your energy management:

Make an energy map

Our ultradian rhythms are affected by other patterns in our routines, which means that as well as having 90-minute productivity cycles, we also have daily and weekly cycles that we need to adjust to. Some of us are more productive in the morning; others are night owls who get their creative juices going at night. For many of us, Mondays and Fridays are when we’re the most distracted at work because our brains are in weekend mode. Tuesdays are often when we find it easiest to concentrate and get our best work done.

So make an energy map! For several weeks, track at which point in the day you feel the most energetic. During those weeks, record your energy levels every half hour with a simple ranking system. Many use a scale of 1 to 10, but for clarity, using a scale of 1 to 3 is very effective (1: little energy, 2: some energy, 3: high energy).

After having made this energy map, you should have a fairly good idea of when you’re at your most energetic. You can now start scheduling your tasks so that your most complex and creative ones are scheduled during high-energy periods.

Develop healthy habits

A myriad different factors affect your energy levels: the amount of sleep you’ve gotten, your diet, your consumption of coffee and alcohol, stress in your personal life, or how recent your last holiday was.

To keep your energy levels up, it’s important that you value moderation with all the things above. Get enough sleep to work productively; Chris Bailey recommends trying to wake up and fall asleep naturally without setting an alarm. Of course, this may work only if you’re on holiday or have flexible work hours. But it is a good practice to have when your schedule allows it, and lets you get more in sync with your natural cycle.

Another good thing to do is to limit your consumption of stimulants like coffee that interfere with your natural rhythms: or, you can try to time your coffee break to be in sync with your energy levels. What food you eat also has a big impact; while high fat, high sugar foods contain instant energy that give you a momentary high, it’s often followed by a low that makes your overall productivity gains pretty minimal.

Take a Nap

You can force yourself to work through a trough, but you probably won’t get much done. These are moments when you feel fatigued, when you read the same sentence three times without absorbing its meaning, or when you suddenly jolt after realizing you closed your eyes for a few minutes at your desk.

During these moments, it can be really beneficial to take a quick power nap: you’ll feel rejuvenated and have newfound energy after that short mental break. Companies like Google, Nike and Huffington Post, are among the few who encourage their employees to take naps throughout the day to boost productivity. We think they’ve got it right: in the US, drowsiness costs businesses $18 billion a year in lost productivity.

Changing up your day-to-day routine, whether it’s by taking a 15 minute break, a quick nap, or changing your work hours to better fit your energy levels, should be something that’s encouraged by employers, not frowned upon. As our understanding of productivity and human psychology develops, our workplaces should change with it.