WHOOP is decoding the sleep-exercise connection.
What’s happening: In a year-long study analyzing 4M+ nights of sleep from nearly 15K users, WHOOP researchers found that strenuous evening workouts delay slumber, reduce sleep quality, and hinder recovery.
Dose-dependent. The study introduced a “strain x timing” model, showing that intense workouts within four hours of bedtime correlate with:
- 36–80 minutes later sleep onset
- Up to 14% shorter sleep duration
- Elevated resting heart rate
- Significantly reduced heart rate variability (HRV)
TL;DR: The higher the strain and closer to bedtime, the more sleep suffers.
On time. While light to moderate workouts ≥4 hours before sleep had little effect, WHOOP’s findings suggest those training in the evening should either exercise earlier or reduce intensity to preserve recovery.
Dialed in. As wearables guide more real-time health decisions, WHOOP’s data-backed insights could shift how athletes—and everyday users—optimize performance and rest. And with sleep tied to longevity, metabolism, and mental health, timing workouts could be as important as doing them.
Takeaway: With its growing dataset and clinical collaborations, WHOOP’s fitness tracker looks more like a predictive health platform.
