Sleep-disrupting noise: More than loudness matters

Since noise can increase heart rate and accelerate brain waves, it can easily wake you up during the dozing-off phase, notes a medical specialist. Photo: dpa

Pyjamas on, lights out, into bed and on to dreamland – unless, that is, some noise won’t let you sleep. Why can it be so disruptive, and what can you do if people are partying well within earshot or your partner is snoring?

The disruptive effect of noise on sleep “naturally depends on what kind of noise it is,” says Dr Eva-Maria Elmenhorst, acting head of the Department of Sleep and Human Factors Research at the German Aerospace Centre’s Institute of Aerospace Medicine.

Since noise can increase heart rate and accelerate brain waves, it can easily wake you up during the dozing-off phase, notes Elmenhorst, a medical specialist in physiology whose research interests include sleep loss, sleep-wake regulation and cognitive performance.

It’s important, she says, whether the noise is continuous or intermittent: A ticking clock or snoring is more disruptive to sleep than the humming of an air-conditioning unit, for example.

Also playing a role is the sound pressure level of the noise, a measure of its intensity. The degree to which it stands out from background noise is a key factor, because the louder the latter is, the softer you’ll perceive an additional noise to be.

A further factor is whether the onset of the noise is sudden or gradual. Sudden noises are more likely to wake you up than those that slowly get louder, Elmenhorst says.

Having said that, people react to noise very differently, she remarks. Although studies on traffic noise show that levels around 65 decibels – that of normal conversation - wake up almost everyone, if you’re very tired you can even fall asleep in extremely loud surroundings.

“We know that some adolescents fall asleep at night in the disco despite the unbelievable racket around them.”

Your attitude towards a noise also plays a big role, according to Dr Karl-Heinz Ladwig, a professor of psychosomatic medicine and psychological medicine at the Medical Faculty of the Technical University of Munich: “A person can react very differently to a noise stimulus, depending on how they judge it.”

He gives a hypothetical example: a father who dozes in the garden despite children playing nosily nearby. The father incorporates the noise as a positive stimulus pattern into his sleep because it signals to him that all is well, Ladwig says.

Similarly, he explains, if you have a negative attitude towards a noise source, you’ll perceive the noise more acutely. In any case, long-term exposure to noise that disrupts sleep can be harmful to your health, in particular to your cardiovascular system.

There are various ways to deal with a noisy sleep environment. Being relaxed when you go to bed is important, says Ladwig, who recommends a pre-bed breathing exercise: Slowly inhale and exhale – the latter audibly through pursed lips if you like - seven times. This lowers blood pressure, he says.

Some people use sleep aids that produce white noise - a monotonous sound experienced as pleasant, such as ocean waves or leaves rustling in the wind - in a noisy environment.

The effectiveness of such aids remains unclear, however, says Elmenhorst, noting that while some studies have found white noise to have a positive impact on sleep by masking certain disruptive noises, other studies have shown the opposite.

“It still has to be treated with some caution,” she says, and advises that sleep aids in general be used in exceptional circumstances and for a short time only to keep yourself from becoming dependent on them.

Furthermore, it’s important to practise proper sleep hygiene, she says. This means using your bed only for sleep, and not to eat or watch television on. Avoid exercise and a heavy meal in the hours before bedtime, as well as blue light from electronic devices.

You shouldn’t drink coffee within about six hours of going to bed, and drinking alcohol is a bad idea too. Although it can help you feel sleepy, says Elmenhorst, it can also make you wake up earlier and more often, thereby robbing you of a good night’s rest. – dpa/Valeria Nickel