A new study suggests that bad, scary dreams can actually be helpful.
The University of Geneva reports that researchers analysed people who experienced them and found that when they awoke, they were much more effective at responding to fear-inducing situations.
The study involved using an EEG to measure brain activity while the participants slept.
Throughout the night, the subjects were awoken numerous times and asked if they'd had a dream that had frightened them.
The results allowed researchers to draw a number of conclusions, which you can learn more about in the video above.