The way you sleep can have a massive impact not only on your health - as certain positions can increase the likelihood of dementia, heart problems and back pain - but also your dreams.
From sexual dreams to nightmares and the reason you wake up grumpy, here are the four most common sleeping patterns and their repercussions:
1. On your front
Also coined the "free fall" position, research from Hong Kong's Shue Yan University found front sleepers are more likely to have sexual dreams.
Researcher Calvin Kai-Ching Yu, asked 670 students to fill out surveys about their dreams, asking questions around frequency and themes.
From participants who slept on their front, the researcher found a strong theme of "erotomania", where a person believes they have a secret admirer, often a famous person.
This position can lead to back issues and tension in the body.
Rishi Loatey from the British Chiropractic Association explains that sleeping on your front may cause overstretched muscles in the neck and pinch nerves, leading to headaches, a stiff neck and tight shoulders.
2. On your left side
If you suffer from heartburn, you may want to train yourself to sleep on your left side.
The Journal of Clinical Gastroenterology found that lying on the left side can help reduce acid reflux symptoms.
For pregnant women, lying on their left can relieve the pressure of the uterus on the liver.
Research has found that those with a tendency to sleep on their left side are more prone to nightmares. A survey showed 41 per cent of left side sleepers reported bad dreams, while only 15 per cent of those who sleep on their right had nightmares.
3. On your right side
A study from Stony Brook University in New York found sleeping on the right reduces a person's risk of developing Alzheimer's disease.
The theory is that lying on the right helps clear waste from the brain, making the development of neurological diseases less likely.
Findings from bed makers Sealy in the UK show right side sleepers had a seven per cent higher likelihood of waking up in a bad mood.
Experts at the University of Auckland also found pregnant women who sleep on their right side have restricted blood flow, posing risk to their baby.
4. On your back
For those concerned about wrinkles, sleeping on your back could stave off signs of ageing in your face.
According to cosmetic surgeon Dr Goesel Anson: "Because your face isn't being pressed firmly into a pillow for six hours or more at a time, you're less likely to get wrinkles and spots," he told The Sun.
Lying with your face skyward can increase the likelihood of airway obstruction.
The British Snoring and Sleeping Apnoea Foundation notes those who sleep on their backs are more likely to snore because of the impact of gravity on the airwaves.
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