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4.0 Measuring Skin Temperature

The WHOOP 4.0 has the ability to measure skin surface temperature through its sensor, and after adjusting to your baseline, will inform you if/when your skin temperature may be deviating from its baseline. These insights are available to view on the 4.0 Health Monitor (Dashboard). 

How WHOOP measures skin temperature: 

  • By using personalized ranges similar to Respiratory Rate (RR).
  • Shown as a +/- in degrees, as compared to the 90-day baseline (1.9 standard deviation).
  • Measured during sleep and averaged across sleep time. 
  • Low temperature + high temperature messaging.

NOTE: Skin temperature is NOT core temperature. = Wrist temperature, not body. 


What’s the difference between skin temperature and body temperature? 

Skin temperature is a measure of the temperature on the surface of your skin. Skin temperature varies more frequently than body temperature, and can indicate potential illness or problems if outside the normal range. 

Why is knowing skin temperature helpful for the average person? 

By understanding what normal/average metrics are, you'll be able to to identify and precaution extremes: when your skin temperature deviates to an extremely low range (aka hypothermia + danger of death), or when your skin temperature rises too high (fever, heat exhaustion). 

Examples of low temperature messaging (including but are not limited to): 

  • Exposure to cold weather
  • Taking certain medications 
  • Illness 
  • A change in WHOOP location on your body 

Examples of high temperature messaging (including but are not limited to): 

  • A microclimate created a sleeve or external heat source during sleep
  • Your body fighting an illness
  • Overexposure to heat
  • A change in WHOOP location on your body

Why is skin temperature only measured during sleep?

This measurement process aligns with the current WHOOP model of calculation for Heart Rate Variability (HRV), Respiratory Rate (RR) and Resting Heart Rate (RHR).

How do skin temperature deviation alerts work? 

Our alerting threshold is wider than your typical ranges. Rather than constantly alerting members about every little deviation (and causing unnecessary or excessive alarm), our aim is to focus on unique events, and using a standard deviation (1.9) as the threshold for alert. 

What are the official averages for skin temperature?

Skin temperature for members is calculated using a personalized baseline. We use the member's previous 90 sleeps to come up with their average, to then determine their baseline - and compare that to the previous 30. In line with how WHOOP measures respiratory rate, an individual's skin temperature range is calculated using their 10th and 90th percentiles. On average, there is less variance with skin temperature, so a wider range is allowed. 

Why am I not seeing my Skin Temperature metrics in the Health Monitor?

It takes 7 days for your Skin Temperature range to fully calibrate. After that, you'll be able to view your daily Skin Temperature metrics directly in the Health Monitor. 

Related articles: 4.0 Sensor Feature: Measuring Blood Oxygen Levels (SPO2)

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