AndreyPopov via Canva.com

Until just a few years ago, we relied on our instincts. Today, we believe that wearables can provide better information about how we should feel. Discover which nighttime metrics can actually be useful.

Admittedly, it's impressive what a watch on your wrist or a ring on your finger can measure. Modern fitness trackers collect countless vital signs throughout the day and analyze, for example, whether we’ve slept well or poorly, moved enough, or are possibly under too much stress at work. These insights can motivate us to adjust or optimize our behavior and habits to improve our performance.

It’s tempting to fully rely on these measured data. But that also comes with risks. Instead of sensing our body's signals and adjusting our behavior accordingly, we blindly follow an app and gradually lose touch with our body awareness. We should instead strive to reconnect with our body and use wearables only as a backup. For instance, we can use them to check whether a bad feeling is misleading or if our body really does need more recovery. In general: if you notice a trend in the data or a night significantly deviates from the norm, you might want to adjust your (training) plan.

The Most Important Metrics

According to health and performance researcher Dr. Peter Tierney, if you use a watch or ring, you should focus on these 5 metrics measured during the night. The first three can be tracked even without wearables.

1. Resting Heart Rate

An adult’s resting heart rate typically ranges from 40 to 100 beats per minute. A lower resting rate is associated with better cardiovascular fitness and a lower risk of mortality. An elevated rate can indicate illness and is also a marker for how the body responds to training loads.

2. Sleep Duration

Most adults need 7 to 9 hours of sleep to perform well and stay healthy. The ideal amount varies from person to person. Generally speaking: the younger you are, the more sleep you need. It’s been repeatedly proven that sleep duration is crucial for promoting health, reducing mortality risk, and aiding recovery.

3. Sleep Timing

The timing of sleep plays a vital role in sleep quality and daytime performance. Regular sleep and wake times are associated with lower mortality risk. Some researchers even consider "regularity" more important than duration.

4. Heart Rate Variability (HRV)

HRV shows how your body responds to training, travel, or stress. A high HRV is a sign of overall health and fitness, while a low HRV can indicate stress or overtraining.

Track medium- to long-term trends and significant deviations from your baseline. Large changes (up or down) should prompt a reassessment of your training intensity.

5. Body Temperature

Fluctuations in body temperature can reveal much about your recovery and general health. It may rise if you've eaten late, consumed alcohol, or exercised. A sudden increase can also be a sign of illness. Women can track their menstrual cycle: body temperature typically dips in the first half and rises slightly in the second half of the cycle.

Conclusion

Wearables provide fascinating insights. But as helpful as this data can be, it does not replace our own body awareness. Quite the opposite! Anyone using wearables should see them as a supplement, not the sole guide. What matters is correctly interpreting trends, pausing when something seems off, and consciously tuning into your body. Only then can we achieve a healthy balance between technology and self-awareness.