Matt Berical over at Van Winkle looks at a couple of studies that suggest the way we sleep influences the way we dream. The first was published in the journal Sleep and Hypnosis back in 2004, and involved 63 volunteers who were asked to sleep either on their left side or their right side. They were then asked to fill out a sleep quality survey upon waking. The survey covered dreams and nightmares, their vividness, and how the participants felt in the morning.
The researchers found that the left side group were far more likely to have nightmares. They report that 40.9 percent of the volunteers reported having disturbing dreams, compared with just 14.6 percent of those who slept on their right-hand side. The right side group were more likely to remember dreams involving feelings of relief or safety, but they also reported lower quality sleep overall.
While the study had its limitations - a small sample size and self-reported results - it does indicate that there could be a difference in dreaming depending on how we're lying in bed.
"Our preliminary observations indicate that dreaming and sleep quality are associated with underlying brain functions and may be affected by body posture," concluded the researchers. "Future research also needs to show how individuals who are skilful in controlling their dreams by hypnotic manipulations or lucid dreaming change their dream process by intentionally changing their posture."
Then there's the 2012 study carried out by researchers from Hong Shue Yan University in Hong Kong. They looked at the habits and sleeping positions of 670 adults and found that those who slept face down had the most vivid dreams: ones involving UFO sightings, love affairs, being locked up, being unable to breathe, or having a sexual relationship with someone famous.
"This effect cannot be fully explained by personality factors, which are merely weakly associated with sleep position," concluded researcher Calvin Kai-Ching Yu, suggesting that sleeping position does indeed influence dreaming. There's also some evidence, albeit anecdotal, that sleeping at an incline makes dreams more vivid - the thinking goes that we're closer to wakefulness when we're closer to the standing position.
No conclusive proof at this stage then, but certainly something to think about the next time you go to bed. If you're in the mood for a vivid dream (or nightmare), try sleeping face down or on your left side - but don't say we didn't warn you.