For World Sleep Day on March 13th 2020, Polar UK GB Running Coach, Nick Anderson, provides the lowdown on Polar’s sleep analysis feature Sleep Plus Stages, as well as why we should place a key emphasis on sleep for increased exercise performance.

Sleep is a vital part of everyday life for humans to function, but every day new findings are uncovered that highlight the power of good quality sleep. Not only does sleep impact upon the body’s ability to recover and repair, there is also a beneficial effect on wider mental and physical health and, perhaps most critically, the prevention of disease.

For frequent gym goers and runners, it is essential for recovery from training and improved running performance.

Top ten reasons why we should incorporate sleep as part of our exercise routine:

  1. Sleep is crucial for recovery from the daily stresses of life and work.
  2. Quality sleep plays a critical role in enabling the body to respond to the training stimulus and make physiological adaptations.
  3. It supports restorative functions like muscle growth, tissue repair, protein synthesis and growth hormone release which occur mostly during sleep.
  4. Inadequate sleep has negative effects on cognitive function, mood and motivation.
  5. People with poor and short sleep duration tend to weigh significantly more than those who get adequate sleep.
  6. Poor sleep can affect training and competition directly, through fatigue.
  7. Poor sleep can affect training and competition indirectly, through increased performance anxiety.
  8. Sleep disturbances can increase the risk for sickness and exercise-induced injuries.
  9. Risk of increased inflammation due to a surge in your body’s production of inflammatory cytokines, alongside a reduction in inflammation-fighting proteins.
  10. Research shows that sleeping 7-8 hours a night of good quality sleep will help you live longer!

The Polar Vantage series and Ignite (featured here is the Polar Ignite) offer the ability to track sleep and review broad metrics through the Polar Flow app. It’s easy to believe you are getting 7- or 8-hours good quality sleep every night, but sleep tracking can reveal much more about what is happening during the night.

  • Sleep Plus Stages gives insights into the amount and quality of your sleep based on an automatic measurement.
  • It measures multiple sleep metrics reflecting the quality of your sleep. These parameters, together with sleep duration, are summarized into a Sleep Score.
  • Sleep Plus Stages shows detailed information on how your sleep cycled through awake and different sleep stages: Light sleep, Deep sleep and REM sleep.

What are the different sleep cycles?

Usually sleep cycles proceed from Light sleep into Deep sleep and then back up to REM sleep. A typical night’s sleep of a young healthy adult consists of 4 to 5 sleep cycles. This equals a sleep time of approximately 8 hours.

Light sleep
Light sleep serves as a transition stage between wakefulness and the deeper stages of sleep. You can be easily awoken from light sleep since your responsiveness to the environmental stimulus remains quite high. Light sleep also promotes mental and physical recovery, although REM and deep sleep are the most important sleep stages in that regard.

Deep sleep
Deep sleep is the stage of sleep where it is hard to be awakened since your body has little responsiveness to environmental stimulus. Most deep sleep occurs during the first half of the night. This sleep stage restores your body and supports your immune system. It also affects certain aspects of memory and learning.

REM sleep
REM stands for Rapid Eye Movement. In REM sleep your brain is active but your muscles are inactive to avoid acting out dreams. Just as deep sleep restores your body, REM sleep restores your mind, and enhances memory and learning.

Frequently having nights without adequate deep sleep periods and with a higher resting heart rate, is an indicator that your body is not fully recovering and will leave you feeling tired and lethargic the next day.

The Polar Ignite and Polar Vantage series also offer a Nightly Recharge feature. Your nightly recharge status reflects how your body was able to recover from training and stress. It combines information on how well your autonomic nervous system (ANS) calmed down during the early hours of your sleep and how you slept.

Banishing phones, tablets, laptops and TVs from the bedroom, and avoiding caffeine, sugar and alcohol late at night can increase the level of continuous sleep and significantly reduce your heart rate during sleep. Polar have also recently introduced the new Serene feature – a breathing technique tool that provides a means of relaxing yourself ahead of going to sleep.

How does sleep impact upon sport performance?

So, in day to day living, good quality restorative sleep will help you feel refreshed and more alert the next day. However sleep plays an even greater role in recovery from training, for those involved in endurance sports or enjoy training regularly at the gym.

For endurance athletes, recovery and good-quality sleep play a critical role in enabling the body to respond to the training stimulus and make the physiological adaptations that ultimately make you faster and stronger. We have all experienced those periods of a season when performances are not quite where we hoped. Niggles are becoming more frequent and there is a general drop off of form and motivation. It’s easy to fixate on making changes to our training plan or our nutrition, but the issue can often lie in those hours we are asleep. If our body is unable to drop into a deep sleep phase, it is harder for the body’s recovery to take effect.

Polar offer a significant step forward in offering endurance athletes a deeper understanding of what is happening in their sleep and how this may be playing a part in their recovery.

Improvements in regular sleep may well be the piece of the jigsaw that once addressed will see the big leap in performance that had previously seemed out of reach. So the old mantra of ‘eat, sleep, train, repeat’, has never seemed more apt.

Polar is one of the first-ever sports watches to offer a tailored approach to sleep, with the advanced Sleep Plus Stages and Nightly Recharge features. View the full range at