If you follow any kind of professional athlete or fitness enthusiast, you might have noticed a common thread throughout their workouts—a black band known as the WHOOP. The innovative tech brand, thought up by three Harvard grads, is on a “mission to unlock human performance”, and while it was initially created for elite athletes to better track their performance levels on any particular day, it has since been made available to fitness fanatics everywhere, allowing everyone to deep dive into their body’s overall performance.

The WHOOP isn’t just like the run-of-the-mill fitness band you’ve probably already tried out, but instead, offers up much more detailed fitness and health monitoring that is completely personalised, actionable, and gets into the real nitty-gritty of how your body can perform at its best. As a brief explainer, the tracker focuses on recovery and heart rate variability (HRV), taking note of data like your heart rate, sleep, temperature and strain to provide your daily recovery rate, which in turn, allows you to better understand why your body might be peaking, or feeling drained.

Safe to say, I was intrigued. As the end of the year approached, it seemed like a fitting time to put the WHOOP to the test. After all, at this time of year, I really need my energy to be at an all-time high, but the inevitable festivities make that task seem near impossible (anyone else?). Here, a deep dive into everything you need to know before trying it out for yourself.

The WHOOP covers three main areas — sleep, recovery and strain — allowing you to understand your body (and energy levels) in an entirely new way. Basically, what sequence of actions, or lack thereof, lead you to feel sick, tired, or fatigued, or what practices make your body peak on certain days and times.

I’ll admit, it all seemed pretty daunting at first — especially when downloading the app and seeing just how intensive the data provided was. The WHOOP takes four dates to calibrate your body, and after that, it’s made a little easier with the personalised coach (almost like a PT in your hands) who helps explain exactly what everything means (and then, most importantly, how it relates to your own personal recovery).

The tracker is able to tell you the strain of your workout on your body, how well and long you’re sleeping, and how well your body is recovering from your workouts. From here it helps you understand what habits or priorities you need to shift. Meaning, it can calculate what you need to do to be performing at your absolute best, like suggesting adding in an extra few hours of sleep or skipping that extra cup of coffee in the morning and that glass of vino in the evening.

The device comes as a band, just like a fitness watch, and is designed to be worn 24/7. Admittedly, while I got the band in a stone colour with a gold clasp (something I thought would blend in a little more than a black band) it did take some getting used to wearing. That being said, after a few days it became an extension of my wardrobe that I didn’t think too much about. You can also get the brand’s training packs which provide sports bras or leggings that hide the tracker if that’s what you prefer.

In terms of if it’s hard to use, the short answer is no — simply place the tracker on your wrist and go about your life as normal, remembering to place the charger on it at night (or whenever best suits you). The only difficult thing is really getting to understand and interpret what the data is telling you about your body and performance. Each morning you’re sent an easy to understand update that breaks all the data down, and for me, oddly enough this has become one of my favourite morning activities.

For me, one of the main areas I was interested in exploring was my sleep and a real selling point for the WHOOP. I’m sure I’m not alone when I say, I’m a bad sleeper. I always have been and have tried just about everything under the sun to get myself to catch more ZZZ’s—from lavender sprays to no technology before bedtime, you name it.

As WHOOP knows, sleep is one of, if not the most important thing you can do to improve your overall wellbeing, and beyond tracking just how many hours you sleep a night, WHOOP also analyses the quality of sleep you’re getting.

Every night, the band calculates sleep performance by measuring the sleep you got compared to the sleep your body needs to perform at its absolute best. It provides a morning Sleep Score from 0 to 100%, and once it gets enough data, the Sleep Coach provides personalised bed and wake times based on daily effort and performance (including sending out alerts to let you know it’s time to hit the pillow, something I personally found really helpful).

If one of your main goals is to ensure that you’re getting enough sleep, the WHOOP is really unrivalled in the data it offers, and after about a month of using the tracker consistently, I was able to make some changes that really shifted the thinking around my sleep patterns.

After wearing the WHOOP for just over a month, safe to say I came to rely on its data, especially when it came to my sleep.

But not just that, I picked up the Keep It Cleaner running program while wearing the tracker (the fitness app created by Steph Claire Miller and Laura Henshaw), and because I was new to running weekly, the WHOOP allowed me to determine which days were the optimal ones to go for that run and perform better and better each time.

The WHOOP Strap comes free with a monthly subscription, starting from $44.