If you have a lot going on in your life, chances are that mild stress is pretty much inevitable throughout your days. Stress can be caused by anything from hugely complicated situations to minor inconveniences, so you're not alone if it seems like all the little things are bothering you. You might think that the stress comes to an end the second your head hits the pillow at night. However, a recent study shows that the effects of stress, relating to your dreams and the cells in your body, can linger.
First and foremost, there may be a reason why you've been dreaming a lot more than usual lately: the culprit is stress. There's already significant research available to explain why mood disorders (such as depression) can disturb typical REM sleep patterns, but little literature has assessed how such sleep changes link to molecular level changes in our brains — until now.
Researchers from the Surrey Sleep Research Centre at the University of Surrey conducted a nine-week study in effort to gain a deeper understanding of how stress and increased REM sleep alter the molecular patterns of our brains. To do so, the team introduced mice to several different mild stressors (e.g. a predator's smell). The findings were striking: the stressor-exposed mice started to show signs of depression, foregoing pleasurable activities and neglecting self-care.
Now, onto the sleep aspect: after closely analyzing the stressor-exposed mice's sleeping patterns, researchers found that the "duration and continuity" of REM sleep increased, as well as certain "specific brain oscillations characteristic of REM sleep." Non-REM sleep saw no changes. Why the changes? They explained that they were directly linked to the regulation of stress hormones and the effects of stress on the brain.
Still, the researchers wanted to get to the bottom of everything: to obtain a comprehensive understanding of the connection between stress, its hormones, REM sleep, and the specific genes we carry. In pursuit of this, they employed machine-learning in order to single out groups of genes that were able to predict observed sleep, behavioral and hormonal characteristics. Finally, they got an answer. The data that they had observed showed that REM sleep, stress hormone regulation and behavioral displays of depression were "closely associated with molecular pathways involved in the death and survival of cells in the brain, primarily in the hippocampus."
All in all, the results of this study can lead future researchers (and curious readers) to get a better grasp on understanding how stress and mood disorders correlate, and where sleep fits into the whole picture. Even though it feels like your brain is basically turning off, a ton happens during sleep. "The comprehensive analysis of the behavioral changes in combination with the sleep and gene expression analyses make a strong case for the important role of REM sleep in the brain response to stress," Dr. Mathieu Nollet said of the study's findings. Next time you feel stressed, notice how your sleep patterns change — and see if your dreams get a whole lot more vivid than usual.