White noise gets all the attention. But sleep researchers actually distinguish between several "colours" of noise, and they do not behave the same way in your brain. Picking the right one is the difference between sound that lulls you under and sound that gives you a low-grade headache by 6am.
What "colour" of noise even means
Like light, sound has a spectrum of frequencies. Each colour of noise is a different distribution across that spectrum. The names are borrowed from light - white contains all frequencies equally, the others are weighted differently.
That is the whole concept. The fact that brown noise is named after Robert Brown, who described random motion in molecules, is a fun aside that no one needs to remember.
White noise
Equal intensity at all frequencies. It sounds like static, an untuned TV, or a roaring fan. Because it covers the whole spectrum, it is the most effective at masking sudden noise events - a slammed door, a passing siren, a partner shifting in bed.
The downside is that to many people, especially on headphones at sleep volume, white noise sounds harsh. The high frequencies push at the ear in a way that can feel almost stressful. If you have tried white noise and it made you wired rather than calm, you were not imagining it.
Pink noise
Pink noise has more energy in lower frequencies and less in the high end. It sounds like steady rainfall, wind through trees, or a soft waterfall. The roll-off in the highs is what makes it sit better on the ear.
There is genuinely interesting research linking pink noise to deeper slow-wave sleep, particularly in older adults. The findings are early but suggestive enough that pink noise has become the go-to recommendation for "I want sleep audio that might actually do something."
Brown noise
Brown (or Brownian, or red) noise weights even more heavily towards low frequencies. It sounds like distant thunder, ocean waves at depth, or a jet engine heard from far away. Many people describe brown noise as the most relaxing of the three - a deep, enveloping rumble rather than a hiss.
Brown noise has become the favourite of people with tinnitus, anxious thoughts at night, or ADHD. There is an obvious reason: low frequencies vibrate the ear and skull in a way that feels physically grounding. If you have not tried it, it is worth a week.
Green, blue, violet... the rest
Green and blue and violet noise exist as technical categories but are mostly marketing labels in the sleep app world. Green noise sits in the middle range and is often described as "outdoor ambient." Blue and violet are highly weighted to the high frequencies and are not pleasant to fall asleep to.
How to actually use this
There is no single right answer. The frame that helps is mask versus lull. White masks - it is loud and broad and covers up environmental noise. Brown lulls - it sits behind everything and softens the nervous system. Pink is the gentle middle.
A bedside speaker is fine, but if you have a partner who does not want it, a pair of sleep headphones makes the choice personal. For tinnitus specifically, brown noise and looped natural soundscapes work best - we put together a small range of tinnitus sleep products that focus on this.
Try one colour for a full week before changing. You are looking for the one you fall asleep to fastest, not the one that sounds best in a thirty second sample on YouTube.
"I had been using white noise for years and never realised it was actually keeping me on edge. Switched to brown noise and fell asleep in eight minutes the first night. Total game changer."
- Sarah K., Sydney ★★★★★
"My tinnitus used to wake me at 3am every single morning. Brown noise on the sleep headphones drowns it out completely. First proper sleep in two years."
- David M., Adelaide ★★★★★
