You’re not alone.

Hours-long YouTube videos of nothing more than rain and thunder have racked up tens of millions of views, as people crave an elusive and soothing deep sleep even when the weather is dry.

We’ve explored why it works, how it works, and explored other similar sounds that could help you sleep.

Why does rainfall make us feel sleepy?

It’s part physiological (i.e., physical), and part psychological (i.e., mental).

On rainy days, the moisture in the air and lower air pressure can reduce the overall oxygen level in the air. And we’re more likely to ‘wrap up warm’ – both of which can making us feel sleepier, even when sat indoors looking out at the rain.

At the same time, our levels of melatonin — the sleep hormone — cycle with the daylight, increasing at nightfall; we’re hard-wired to sleep when it’s dark. It’s why some people at extreme latitudes find the winter months, with their shorter periods of daylight, especially tiresome. And it’s why, on rainy days when the sky is grey and dark, we automatically begin to feel more tired.

Over years, those of us who live in rainy parts of the world have been conditioned to associate the sound of rain — with its gentle, constant patter — with a feeling of comfort, warmth and sleepiness.

Isn’t rainfall a kind of ‘white noise’?

Not exactly. White noise is a technical term for the kind of ‘static’ audible when you tune an analog radio to an unused frequency.

It’s a noise that’s broadly spread across the audible spectrum: an equal mix of high, mid-range and low frequency sounds. Rainfall is similar, in that raindrops hitting different surfaces (like grass, roofs, cars, roads, etc.) generate sounds of different frequencies, mimicking the broad-spectrum sound of white noise.

A 2017 study found that adults fell asleep 38% faster while listening to ‘white noise’, so it’s perhaps not surprising that people have learned from their own experience that rainfall similarly helps them sleep.

Why is ‘white noise’ white? And are there different colors of noise?

White noise is analogous to white light; just as full-spectrum white light can be broken down into different colors, white noise can indeed be broken down into different ‘colors’ if you focus on just some of the possible sound frequencies.

Blue noise emphasizes high frequency sound, and violet higher still. Grey noise has a mix of low and high frequencies, but little of the mid-range. And pink noise turns the volume up on low frequencies, and down on high frequencies — but still has a mix of all three. Brown noise forgoes high frequency sound entirely, and dials up the low even more.

Because of the frequency range that pink noise takes up, it can make the most effective sleep-aiding sounds. And there are many natural pink noises that can help us sleep.

Examples of effective sleep sounds

There are endless sleep sounds that might work for you, but they are commonly a whooshing or low rumbling.

Imagine, if you can…

• The deep growl of distant thunder
• A waterfall crashing on rocks
• Waves breaking softly on a beach
• A fireplace’s gentle roar and crackle
• Leaves rustling underfoot
• A cat’s contented purring
• The sonorous din of an airplane’s jet engines
• The clickety-clack of a train on its tracks
• The constant grumble of tyres on a long car journey

Those living in the city may even find the sound of passing vehicles helps them sleep. And newborn babies have been shown to fall asleep faster when listening to ambient sounds that mimic the womb: a heartbeat and rushing blood.

What makes a great sleep sound?

Of all the things that might help you drift off, there are a few of common features:

• Monotony and repetition — Free of the dynamism and interest that comes with carefully crafted music, sleep sounds are design not to hold your attention.
• Familiarity — Many of the examples we listed above are sounds that we associate with calming or relaxing moments, like being on vacation or bundled up warm somewhere. You may even recognize some as times you have fallen asleep before: on a plane or train, or in the back seat of the family car as a child…
• Low volume — Any sound can keep you awake if it’s loud enough. Keep it reasonably hushed.

By contrast, synthesized, high-pitched sounds aren’t good sleep aids, because they often sound ‘alien’ or space-age. Music and conversation aren’t often helpful either, as they can be too detailed and more likely to hold the attention — so turn off the radio!

How does pink noise help us sleep?

Pink noise help us sleep in several ways. Perhaps obviously, it can block out other noises that may keep us awake, and its tediousness can help us enter a more meditative state where sleep comes easily, free from intrusive thoughts.

And, it lacks the kind of sudden or loud interruptions that sends our cortisol levels soaring, so we’re subconsciously lulled into a sense of security and safety — allowing us to literally switch off.

White and pink noise machines

You can buy dedicated machines that generate white or pink noise, and there are lots of choose from — including those aimed at youngsters, those for people on a budget, and those with other functions (like a time-to-wake light or alarm clock).

If you’re wondering which is the best for you, don’t worry — the New York Times has done the research, so you don’t have to.

Everyone loves to sleep — embrace it

Sending your customer to sleep is rarely a good thing, but you can draw links between your products and the wonderful benefits that come with a great night’s sleep — everyone loves one of those!

Homewares brand IKEA spoofed fad products like anti-ageing creams and vitamin supplements, with their bedding products playfully inserted into the scene. The 2020 campaign positioned the brand as sleep experts and appeared on billboards across the UK and Ireland.

Some brands have even found ways to use sleep sounds in recognition that a good night’s sleep is the ultimate luxury.

American luxury car brand Lincoln created The City That Sleeps. It’s an 8-hour long album aimed at New Yorkers who struggle to sleep in the total silence that comes with nightfall in rural or suburban areas. It’s nothing to do with their products, but a lovely way of demonstrating how much they care about their customers at every point.

Staying in the automotive world, Nissan created a lullaby for parents who own their LEAF compact car. The lullaby is designed to help children drift off — a role typically fulfilled by engine noise, but obviously absent in an electric car like the LEAF.

Ask yourself how your business could align itself with the idea of a good night’s sleep. Perhaps you sell glazing, and can cocoon your customer away from a noisy world. Perhaps you’re in the business of window blinds, and can help block out disruptive light pollution…

Audio is your secret weapon

In a world where visual branding is at saturation point, audio is a smart way of creating differentiation for your business.

Audio pieces like those created by Lincoln and Nissan aren’t likely to convert into a sale — nobody is going to spend tens of thousands of dollars because of a playlist or music track — but they can absolutely help to generate positive feeling about your brand, and make people more likely to consider your products.

For commercial audio that’s more of a dream than a nightmare, speak to one of our experts about a free, no-obligation demonstration.