In our relentless pursuit of progress, athletes often find themselves focusing on the absolute minutiae of training plans. While these details undoubtedly play a role in performance, we often overlook the co-importance of two fundamental pillars: nutrition and sleep.

Understanding their vital roles and the intricate relationship between them can unlock new levels of performance and aid in our recovery.

Let's delve into the fascinating interplay between glucose and sleep, illuminating the path to optimal performance.

Internal vs External Load

It should be noted that external load is what is imposed on athletes from a training plan; paces, distances, volume, repetitions etc. Whereas internal load is the response from the body; heart rate, RPE, etc and a consequence of the proposed external load. For example, for a given external workload (distance completed at a certain intensity) an athlete may experience that load very differently due to nutritional or environmental factors driving a much higher heart rate.

The reason this is so crucial is that adaptation to the two is not the same and ultimately our individual adaptation to the training stimulus is the most important factor in performance, not the training itself.

How do you know if you are Recovering well and Adapting to Training?

One measure previously reserved for only elite athletes, but more recently brought to the broader population through wearable technology such as the Oura ring is Heart Rate Variability (HRV). In short, this is a representation of the balance of the sympathetic nervous system and parasympathetic nervous system, or stress balance. There are many ways to measure HRV and Oura’s overnight average is scientifically validated against the gold standard.

There may also be a role for glucose in this recovery and adaptation monitoring, for more on that see below.

Oura and Supersapiens
Picture 1: Heart Rate Variability (HRV) and Resting Heart Rate (RHR) from Oura in the Supersapiens app via integration

Optimizing Readiness

In order to best absorb training stimulus, it is important that recovery is optimized (if this is the goal, though at times carrying extra fatigue is reasonable if it is planned for). This requires appropriate refueling after previous training sessions and appropriate priming for the upcoming training session. It also requires appropriate sleep, as this is where the body recovers and repairs itself.

Stress the Glucose

In much the same way that poor sleep can cause dysregulated glucose homeostasis (see below), psychological or emotional stress can too. Stress itself can drive high glucose as covered in this article. For more on HRV as a measure of stress and glucose see this article by Marco Altini.

The Glucose-Sleep Nexus: A Symbiotic Relationship

The relationship between glucose and sleep is a symbiotic one and something Supersapiens often ask about. This topic was previously covered here, whilst ways you may use CGM to help sleep are covered here. The Oura ring is a market leader when it comes to sleep, with a recent paper displaying their ongoing improvement of their sleep algorithm.

The Impact of Glucose on Sleep

Sleep serves as the critical period for mental and physical recovery and restoration. Sleep is a complex and dynamic process that encompasses various stages, each with its own purpose and impact on our well-being and performance. During sleep, our bodies undergo numerous physiological processes, ensuring optimal functioning during our waking hours.Good quality sleep, the type that helps us feel and perform our best, requires good sleep hygiene which includes an optimal environment. This environment fundamentally hinges on a lack of interruptions to sleep eg noise, light etc and this is where glucose can play a role. There is research suggesting that higher glycemic index carbohydrates (ones that will cause more of an increase in glucose levels) may improve various aspects of sleep. That said, eating too close to bedtime can impact sleep quality.
Beyond this, periods of excessively low glucose or significant drops in glucose whilst sleeping can at times cause awakenings, even if only micro-awakenings. The relationship between these awakenings and glucose dysregulation is well established (see below).

The Impact of Sleep on Glucose

One crucial aspect of sleep is its role in metabolic regulation, including glucose metabolism. Sleep deprivation has been consistently linked to impaired glucose tolerance, insulin resistance, and an increased risk of developing type 2 diabetes. Disrupting the delicate balance between glucose and sleep can have far-reaching consequences for our health and performance. The impact of poor sleep on glucose is something mentioned in our discussion with Matthew Marquardt.

Glucose During Sleep: A Potential Canary in the Coalmine

Many athletes, including Lisa Norden and Gustav Iden, note that during increased training loads or during periods of underfueling their overnight glucose levels can be lower, less variable and the periods of time they spend below 80mg/dL can increase.

This may be a good warning sign for those prone to underfueling their training or may serve as a secondary marker with others such as resting heart rate and HRV to indicate recovery status. This relationship is one that is too early to speculate on, but very exciting and part of the driver for Supersapiens to integrate with Oura.

Optimizing Performance and Recovery: Harnessing the Synergy

To unlock our true potential, it is vital to use both glucose and sleep in our pursuit of optimal performance and recovery. Here are some key strategies to help harness the synergy between them:

  1. Optimal Fueling: Fuel for your output (performance) requirements. Ensuring appropriate protein intake and carbohydrate availability are the cornerstones of nutrition for athletes.
  2. Timing and Quantity: CGM gives improved granularity and insight into timing of intake around activity, as time progresses it may also yield greater insights into the role of carbohydrate dosing and impact on sleep.
  3. Sleep Hygiene: Establish a consistent and regular sleep routine by going to bed and waking up at the same time each day. Create a sleep-friendly environment, free from distractions and electronics. Prioritize relaxation techniques, such as meditation or reading, to unwind before sleep. This will aid in optimal glucose metabolism in the following days.
  4. Training and Sleep: Exercise helps regulate glucose metabolism and promotes better sleep. Getting this balance and relationship right is crucial, this includes timing, intensity and duration of exercise with respect to proximity to sleep.
  5. Recovery: Prioritize and monitor your recovery and adaptation to training. Oura and Supersapiens both play a role in gaining greater insights into these factors and allowing users to modify behavioral factors that may play a role in optimization of sleep and recovery.

By recognizing the co-importance of glucose and sleep, we can optimize our physical and mental performance, enhance recovery, and elevate our overall well-being. Embrace the power of this synergistic relationship and embark on a transformative journey toward a more energized, focused, and vibrant life.


  1. Altini, M.; Kinnunen, H. The Promise of Sleep: A Multi-Sensor Approach for Accurate Sleep Stage Detection Using the Oura Ring. Sensors 2021, 21, 4302.
  2. Cao R, Azimi I, Sarhaddi F, Niela-Vilen H, Axelin A, Liljeberg P, Rahmani AM. Accuracy Assessment of Oura Ring Nocturnal Heart Rate and Heart Rate Variability in Comparison With Electrocardiography in Time and Frequency Domains: Comprehensive Analysis. J Med Internet Res. 2022 Jan 18;24(1):e27487. doi: 10.2196/27487. PMID: 35040799; PMCID: PMC8808342.
  3. Vlahoyiannis A, Aphamis G, Andreou E, Samoutis G, Sakkas GK, Giannaki CD. Effects of High vs. Low Glycemic Index of Post-Exercise Meals on Sleep and Exercise Performance: A Randomized, Double-Blind, Counterbalanced Polysomnographic Study. Nutrients. 2018 Nov 18;10(11):1795. doi: 10.3390/nu10111795. PMID: 30453682; PMCID: PMC6267571.
  4. Afaghi A, O'Connor H, Chow CM. High-glycemic-index carbohydrate meals shorten sleep onset. Am J Clin Nutr. 2007 Feb;85(2):426-30. doi: 10.1093/ajcn/85.2.426. Erratum in: Am J Clin Nutr. 2007 Sep;86(3):809. PMID: 17284739.