White noise and sleep sounds
What studies and expert bodies say
Whether steady white noise helps with sleep has been little studied, and experts disagree. A meta-analysis found more sleep over the whole day in children up to three years, but the studies are small and inconsistent (Ding 2025). A review points out that continuous, louder noise could burden development, while quiet noise may rather help (De Jong 2024).
Volume and distance
Measurements show that many sleep machines get very loud at their highest setting (Hugh 2014). In a further measurement, all devices and apps stayed below the occupational noise limit at their lowest setting; at their highest setting many exceeded it at 10 cm, as if in the cot, but none did from 30 cm (Hong 2021). The researchers therefore suggest: quiet, never the highest setting, not in the cot, at least 30 cm away, and a timer. Moon Hour limits the volume and fades the sounds out by itself; how loud it ends up also depends on your phone’s volume.
If you are worried
Experts recommend contacting your paediatrician or your local out-of-hours medical service if you are worried.
Sources
- Ding et al. 2025: White noise and sleep (meta-analysis)
- De Jong et al. 2024: Continuous white noise during sleep and child development (review)
- Hugh et al. 2014: Sound levels of infant sleep machines
- Hong et al. 2021: Sound output of white noise devices and apps by distance
General information, not a substitute for medical advice.
Sources checked: November 2026