If you live somewhere that was recently hit by a heat wave, you’ve probably spent your nights tossing and turning in bed, trying different positions to get comfortable.
But what does science say about the best sleeping positions?
Studies on many people, from sailors on cargo ships to welders in Nigeria, can help us answer this question, although given how important sleep is to us, it is surprising that very few large-scale studies have been conducted.
First, you need to find a way to find out what position people sleep in.
You can ask, of course, but we only remember the position we were in when we tried to sleep and the position in which we woke up.
To learn more, researchers have tried a number of techniques including filming people as they sleep or having them use wearable technology to monitor their movements.
In Hong Kong, researchers are developing a system that uses infrared depth cameras that can detect the position of a sleeping person even through a thick blanket.
Researchers in Denmark used small motion sensors on the legs, backs and arms of volunteers to establish their favorite positions.
They found that during the time spent in bed, people spent just over half the time on their sides, 38% sleeping on their backs, and 7% on their stomachs.
The older they got, the more time they spent on their sides.
This preference for sleeping on the side is something we develop only as we get older, because children over the age of three sleep on average the same amount of time on their sides, backs and stomachs.
Babies, on the other hand, sleep mostly on their backs because they are put that way in the crib for safety reasons.
So side sleeping is the most common position and we can rely on the wisdom of the masses to choose the best position, but what does the science say?
Snoring
A small-scale observational study in which volunteers were allowed to sleep as they wished found that those who slept on their right side slept slightly better than those who slept on their left side, followed by those who slept on their backs.
Another small-scale study investigated how sailors working on a cargo ship slept and found that breathing problems, such as snoring, were more common when the sailors slept on their backs.
Some snoring is caused by severe obstructive sleep apnea, in which breathing stops and restarts when the person sleeps.
This is more common in people who consistently sleep on their backs.
In contrast, sleeping on the side helps clear the upper airway and prevents the uvula (the fleshy part that hangs in the back of the throat) and tongue from clogging the throat, which reduces snoring.
In fact, in some cases, switching from sleeping mostly on the back to sleeping on the side solves the sleep apnea problem completely.
Sleeping on the side may have other benefits as well.
For example, research on sleep patterns in cargo ship welders in Nigeria showed that back sleepers were more likely to suffer back pain compared to side sleepers.
Personal choice
But this does not mean that sleeping on your side works for everyone or is a panacea for all aches and pains.
It depends on your problem and the exact position you adopt when you sleep.
Researchers in Western Australia monitored the bedroom of volunteers 12 hours a night with automatic cameras and found that those who said they woke up usually with a stiff neck spent more time in what the researchers called “provocative side sleeping positions.”
In this context, this phrase means sleeping on one side in a twisted position, for example, with one thigh overlapping the other and the spine rotated.
In contrast, people sleeping in a straighter, more supportive side position reported less neck pain.
What the study couldn’t decipher is whether the “provocative” position caused the neck pain or people adopted that position because it was the only comfortable one because of neck pain.
So how about having people try sleeping in a new position and then following up to see if it makes a difference in the pain they feel?
In a study conducted with older people who were doing a training program in Portugal, those with back pain were asked to sleep on their sides, and those with neck pain were asked to try sleeping on their backs.
Four weeks later, 90% of the participants said their respective pains had decreased. However, as only 20 people participated in the study it is not possible to conclude that this simple change of position can have such a positive effect on all people suffering from neck and back pain.
As always in the field of scientific research, more studies need to be done.
Position for reflux
or a particular medical problem, it’s not just a matter of sleeping on one side, but one in particular.
When acid reflux occurs, gastric juices rise from the stomach, causing an intense burning sensation in the chest.
Doctors sometimes recommend sleeping elevated by several pillows to relieve symptoms.
If the discomfort recurs, the problem is known as gastroesophageal reflux disease, which can have serious consequences.
It is not clear why it occurs, but one possible explanation is that sleeping on the left side keeps the junction between the stomach and esophagus above the level of gastric acid.
Sleeping on the right side relaxes the lower esophageal sphincter, allowing acid to escape.
Whatever the answer, if you have heartburn, it never hurts to try sleeping more on your left side in the future.
Face down?
And what about those who sleep – a small minority – on their stomachs?
For starters, one study notes that it’s not a good idea if you have jaw pain, not surprisingly.
And what about wrinkles – surely sleeping with your face squashed against your pillow will make them worse?
In a cosmetic surgery magazine, a group of plastic surgeons explained that facial skin is best preserved if you treat it “like a seaweed floating while tied to a stem”.
So the idea is to impose as little pressure as possible on your face while you sleep, and that rules out sleeping on your stomach.
And if preserving your skin is more important than sleeping better or dealing with aches and reflux, then sleeping on your side is not ideal either.
What can we conclude from all this?
First, all things being equal, side sleeping seems to have several advantages, but your precise posture can have an effect on neck and back pain, and the side you sleep on can increase or decrease your heartburn.
Snoring increases if you sleep on your back, but for you it may be the best way to sleep.
It’s worth trying new positions and keeping a diary if your current position doesn’t let you sleep well. But try not to get too obsessed with the different positions, otherwise this preoccupation will rob you of sleep.