Polar Nightly Recharge review

The Polar Nighly Recharge is Polar’s version of sleep tracking which shows you how well you slept and recovered during the night. It consists of two parts: Sleep Charge shows you how you slept and ANS Charge shows you how well your autonomic nervous system calmed down during the night.

I have used many smartwatches and fitness trackers for example from Garmin and Fitbit, but those don’t give you a similar score and insights into your sleep recovery as Polar’s Nighly Recharge. I think the Nighly Recharge is a fantastic feature and I use it daily on my Polar Ignite smartwatch.

If you are interested in the Polar Ignite you can check my comments on it and the end of this article.

Nighly Recharge benefits

How well you recover during your sleep has a huge impact on how you are able to function during the day. Stress from work and strain from training can have an impact on your sleep and the nightly recharge feature can tell you how well you have recovered.

The measurement insights can help you by knowing that you need to take it easy and for example get some more sleep if you haven’t recovered enough. For training purposes, it’s good to know how well you recovered during the night so that you know how hard you should train. Polar even gives you recommendations about training based on your measurements.

I have been using the Polar Ignite smartwatch for three months now and comparing it to the Vivoactive 3 which I used before I think the best feature is the nightly recharge. I really enjoy checking my stats each morning to see my sleep charge score and the ANS charge score.

I think the nightly recharge results do motivate me to go to bed earlier to be better charged for the next day. If I’m feeling tired in the morning it’s pretty much always visible in the nightly recharge results and I think the measurements are really accurate based on 90 days of using it.

How does Nighly Recharge Work

For your body and mind to function properly for work and training purposes it’s essential that you recover during your sleep.

Studies show that good indicators of recovery are sleep and the autonomic nervous system activity. The Polar Nighly Recharge feature combines these two aspects giving you insights on how your body is doing and it’s comparing your nighly results to averages from 28 days.

Nighly Recharge is comprised of two measurements: Sleep Charge shows you how you slept and ANS Charge shows you how well your autonomic nervous system calmed down during the first 4 hours of your sleep. Both of these measurements are done automatically by your smartwatch during the night. The only thing you need to do is wear the watch.

Nightly Recharge shows the results as: very poor – poor – compromised – OK – good – very good by combining the Sleep Charge and ANS charge scores.

ANS charge is calculated based on three parameters heart rate, heart rate variability and breathing rate. The Polar smartwatch uses the wrist-based optical heart rate measurement sensor to get the data for these measurements. According to Polar ” To get a higher ANS charge your heart rate would need to be lower, heart rate variability higher and breathing rate lower than usual.” Heart rate has the biggest influence and breathing rate the lowest.

The ANS charge score is from -10 to +10 with zero being your usual level. Stress, exercising late and illness can elevate your heart rate giving you worse ANS results. My personal observations have shown all of these. For example, when having the flu I did see worse than normal results.

Sleep charge compares your last night’s sleep to your past scores from 28 days. Sleep charge is shown as a score between 1- 100 and shows how much and how well you slept.

Sleep charge is determined as the average of six components under three themes: amount, solidity and regeneration. The six components are sleep time, interruptions, continuity, actual sleep, rem sleep, and deep sleep.

Devices that have the Nighly Recharge feature

The Nightly Recharge feature is unique to Polar and I haven’t seen anything like it on other smartwatches or fitness trackers yet.

Currently Polar has the Nightly Recharge feature on four devices: Ignite, Vantage M, Vantage V, and Vantage V Titan.

The cheapest one of these devices is the Polar Ignite which Amazon.com is selling for $180 in February 2020. I bought it three months ago and have thoroughly enjoyed it. I think it’s the best smartwatch I have had so far and it really provides a lot of value for such a small price.

Polar Ignite – Click to check the current price on Amazon.

Comparing Polar to Garmin I think Polar has recently moved leaps forwards and I think the Polar ecosystem matches Garmins and in some parts goes even beyond it for example with the Nightly Recharge feature combining it to the training recommendations. I must say that I enjoy my Polar Ignite more than the Garmin Vivoactive 3 which I reviewed some time ago. One thing I notice in particular is how easy and fast it’s to start the training with my Polar Ignite when I’m at the Gym. For some reason, I kind of struggled to do this quickly on the Garmin device.

The Polar Ignite has a surprising amount of features for such an affordable device:

  • full-color touch screen display
  • A ton of nighly metrics including breathing rate
  • Nightly recharge functionality showing
  • Fit Spark giving you training guidance based on your nightly recharge
  • Serene – Guided breathing exercise
  • Optical HR measurement and GPS
  • Running Index & VO2Max
  • Structured Workout
  • Indoor and Openwater swimming features
  • Unfortunately no offline music features

You can also check the Polar Ignite review by DC Rainmaker.

Polar Vantage M is also very reasonably priced if you want some more features than on the Ignite. Currently, the Vantage M is sold by Amazon for $220 and you do get pretty much all of what the Ignite has to offer but some additional features like support for more sensors for running and cycling and more battery life for training.

Polar Vantage M- Click to check the current price on Amazon.

I personally haven’t used the Vantage M but some of my friends do and say it’s good. It’s a bit larger than the Ignite so if you have a bigger wrist might make sense to go for the Vantage M just for looks since the Ignite can look small if you have a thick wrist.


Hi! I'm John and this is where I share my tech learnings. As a tech enthusiast and a smartwatch believer (I wear a Garmin smartwatch), I like to read about the newest trends and research new devices. On this blog, I share all the things I learn about smartwatches as I go.

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