All three are masking sounds. All three help you sleep. They differ in where the energy in the sound sits — and that one technical difference produces meaningful differences in how they sound, who tends to prefer them, and what they're best at masking.
What you'll learn
Quick reference table
White noise
What it is: An audio signal containing equal energy across all frequencies a human can hear (roughly 20 Hz to 20,000 Hz). The word "white" is by analogy with white light, which contains equal energy across all visible wavelengths.
What it sounds like: A steady hissing, like a waterfall or like radio static. Slightly higher-frequency overall, so it can feel "sharp" or "thin" to some listeners.
What the research says: White noise is the most-studied sleep sound. It reliably reduces sleep latency (the time to fall asleep), is consistently recommended for infants, and is used in plenty of clinical contexts.
Best for:
- Newborns and infants (the pediatric default after womb sounds)
- Light sleepers in noisy environments
- Dorms, hostels, and shared housing
- Hotel rooms — masking hallway traffic and HVAC
- Daytime focus when total silence is distracting
Detailed feature page: white noise.
Pink noise
What it is: Audio where each octave contains the same amount of energy — which, because higher octaves cover wider frequency ranges, means the energy is concentrated more toward lower frequencies. Mathematically: 1/f energy spectrum.
What it sounds like: Softer, warmer, more "rounded" than white noise. Imagine steady rainfall as a natural reference — that's close to pink noise.
What the research says: A handful of small studies have linked pink noise to improvements in slow-wave (deep) sleep, particularly in older adults, and to memory consolidation overnight. The effects are modest and the research is early, but it's enough to put pink noise on the radar as more than just "soft white noise."
Best for:
- People who find white noise too sharp
- Older adults who want to optimize for deep sleep
- Memory-intensive periods (students, presentations)
- Tinnitus sufferers, who often find pink more comfortable than white
- Daytime focus that's less fatiguing than white noise
Detailed feature page: pink noise.
Brown noise
What it is: Audio with even stronger low-frequency emphasis — 1/f² energy spectrum. (The name comes not from the color brown but from "Brownian motion," which produces a similar spectral profile.)
What it sounds like: Deep, rumbling, weather-like. Distant thunder. Heavy rain inside a parking garage. The bass thrum of a far-off concert venue.
The cultural moment: Brown noise had a major viral moment on TikTok in 2022, particularly within the ADHD community, with many users describing it as "the only thing that quiets my head." Anecdotal but very widely shared, and consistent with the masking benefits applied to focus rather than sleep.
Best for:
- Masking low-frequency disturbances: HVAC, traffic, snoring partners, distant bass
- City apartments and urban environments
- ADHD focus and deep-work sessions
- People who find white and pink noise too "thin"
- Pairing with red light for the most sleep-protective combination
Detailed feature page: brown noise.
Speaker note: Brown noise is bass-heavy, so it sounds richest through a decent speaker or headphones. On a tiny phone speaker, you'll lose some of the low end. A small Bluetooth speaker on the nightstand makes a noticeable difference.
How to choose
- Start with white noise. It's the default for a reason — the most universally tolerated, most-studied option.
- If white noise feels sharp or wakes you, try pink. Same masking benefit, softer texture. Many adults end up here.
- If you live somewhere with lots of low-frequency noise (city, snoring partner, busy street), try brown. The low-end masking is more effective for those specific frequencies.
- For babies under 4 months, start with white noise or womb sounds. These are the most-studied for infant sleep specifically.
- For focus rather than sleep, try brown. Particularly if you have ADHD or just find total silence distracting.
It's worth trying all three for a few nights each — your preference becomes obvious quickly. There's no universal best, only "what works for your ears."
Volume guidance
Pediatricians generally recommend keeping sleep sounds around 50 dB (about the level of a quiet conversation), and keeping the device at least a meter from a sleeping baby's ear. The American Academy of Pediatrics has issued guidance specifically warning against very loud noise machines for infants.
For adults, the goal is volume slightly above the loudest typical disturbance you're trying to mask. If a snoring partner is the issue, the noise needs to be loud enough that the snore doesn't poke through. But once you've got that, more volume doesn't help — and can become its own disturbance.
Combining noise with other sounds
You don't have to pick one and stop. Layering works well — try:
- Brown noise + rain. The brown noise provides the bass masking, the rain adds texture and emotional warmth.
- Pink noise + ambient music. The pink noise masks, the music sits gently on top.
- White noise + sleep timer. White noise for the first 30 minutes (when masking matters most), then everything fades.
Night Light X lets you start any sound from its library, pair it with a warm color, and finish with the sleep timer — a complete bedside audio environment in one app.