Your sleeping position could be triggering your nightmares. Researchers from Yuzuncu Yil University in Turkey reported that people who sleep on their left side are more vulnerable to nightmares. A study published in the journal Sleep and Hypnosis in 2004, which recently gained attention, reported that "dreaming and sleep quality may be affected by body posture."

The researchers recruited 63 volunteers who were randomly asked to sleep either on their right side or left side. They answered a sleep quality survey called Pittsburgh Sleep Quality Index, which included questions about dreams, nightmares and their effects on the participants every day when they woke up.

The results showed that 40.9 percent of those who slept on their left side had nightmares, while only 14.6 percent of those who slept on their right side reported the same. Additionally, the right-side sleepers remembered dreams more vividly, associating them with feelings of being safe. They also had better sleep quality.

The study findings showed that "dreaming and sleep quality are associated with underlying brain functions and may be affected by body posture."

"It is clear that right-side sleepers in the present study had good sleep quality as well as positive dream emotions. Left-side sleepers reported more nightmares compared to right-side sleepers," the authors concluded.