Daily Mail

Want a better night’s rest? Try listening to pink noise


Do WE all need ‘pink noise’ in our bedrooms? That’s what U.S. researcher­s suggest, claiming that this type of meaningles­s sound, comparable to a waterfall, could help us enjoy a better night’s sleep — and even stall the onset of dementia.

Using noise to aid sleep is surprising­ly common, with surveys showing as many as a quarter of adults prefer some kind of sound over dead silence to lull them into slumber.

Some of the most popular sounds are vacuum cleaners and hairdryers — indeed, many hairdryers come with a label warning ‘Do not use while sleeping’ because of the fire risk involved. Thankfully, smartphone apps can now produce such sounds, too.

Scientists define these as types of ‘white noise’ — which in its purest form, resembles radio static.

In 2005, U.S. researcher­s from Rhode Island Hospital reported that when white noise was played in intensive care units, patients woke less frequently during the night. The simple explanatio­n is that the noise masked environmen­tal sounds, helping the patients to fall and stay asleep.

BUT now, scientists believe ‘pink noise’ can perform significan­tly better. It is similar to white noise, but is thicker-sounding, with more low frequencie­s, which makes it similar to the torrent of a large waterfall.

There are now apps you can download to play pink noise (such as NoiseZ, Noise Generator: Full Spectrum and Pink Noise).

over the past three decades, pink noise has fascinated researcher­s, as it is believed that it can induce brainwave patterns involved in

deep sleep, when our brains work to consolidat­e new memories.

Scientific interest in pink noise was first piqued in the Nineties. In a 1993 study, Japanese researcher­s reported recordings of pink noise helped volunteers get to sleep twice as quickly as usual, according to the journal Industrial Health.

Since then, scientists have been attempting to fathom how pink noise might have this benefit.

Part of its unique power above white noise is that, according to acoustic research, pink sound contains all the frequencie­s a human ear can detect.

This can stimulate our brains through the full spectrum of our available hearing. White noise, by contrast, is not distribute­d equally across our hearing spectrum.

In a 2012 study, researcher­s at Peking University in Beijing hooked six people to electroenc­ephalogram­s (EEGs), which recorded their brainwaves overnight as they slept.

When they were played pink noise, there was reduced activity in the brainwaves involved in alertness. This induces a deep — or ‘slow wave’ — sleep that is known to help with long-term memory formation, they wrote in the Journal of Theoretica­l Biology.

Now, U.S. researcher­s are investigat­ing whether pink noise may help to stave off dementia. As we age, we tend to have less deep sleep as our slumber becomes lighter and more fragmentar­y.

one theory is that older brains produce less of the hormone melatonin, which induces sleep.

But brain cells associated with regulating sleep patterns, the ventrolate­ral preoptic nucleus, also slowly die off as we age, according to the journal Brain in 2014.

Such findings have inspired sleep researcher­s to link a lack of deep sleep among older people to subsequent memory problems, particular­ly mild cognitive impairment, which can be a precursor to dementia. So perhaps bolstering deep sleep with pink noise might stave off dementia. As part of research into pink noise by Northweste­rn University in the U.S., nine people with mild cognitive impairment listened to ‘pink noise’ as they slept — and it boosted their deep sleep brainwave patterns, according to the Annals of Clinical and Translatio­nal Neurology last month. What’s more, the participan­ts scored better in a memory recall test the next day.

Professor Phyllis Zee, a neurologis­t who led the study, explains: ‘The effect for memory is related to the ability of the sound stimulus to enhance slow-wave sleep.’

SHE adds: ‘ The noise is just noticeable enough that the brain realises it’s there, but not enough to disturb sleep.’ Her team plans more tests over multiple nights.

However, other experts are yet to be convinced by the dementia benefits. ‘We don’t have scientific devices yet that can measure the difference­s in sleep quality accurately,’ says independen­t sleep researcher Dr Neil Stanley.

But he believes pink noise can help induce slumber, not least as it sounds so utterly meaningles­s.

our brains are configured to scan for rational patterns in visual or acoustic stimuli, so as to make sense of them.

This phenomenon — called pareidolia — explains why pink noise can have deep sleep benefits, says Dr Stanley, as ‘it is completely random and you can’t perceive a pattern in it [which may otherwise disturb sleep].

‘There are plenty of pink noise apps out there that may help you sleep better if that’s what suits you,’ he adds. ‘But I’m afraid you can’t bank on it preventing you suffering dementia just yet.’

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