“Total sleep duration mirrors the stage-specific trends: nights under 55 dB hover around 6¼–6½ hours, but once noise breaches the upper-50s the average night shortens by nearly an hour”
Apple Watch data says nights above 55 to 60 dB cost nearly an hour of sleep. There is no sample size, no methods and no control for snoring partners or city living. The sleep stages are wearable guesses. The page ends with an offer for 100 biomarkers for $190.