No, I will not be covering that one Meek Mill song like the title might suggest. Even though I’m someone who does not remember my dreams very often, when I do dream it’s often something so real I can’t tell if it actually happened, or a nightmare that also seems real enough to be a possibility. I don’t have many fantastical unrealistic dreams anymore as I’ve noticed. To me, dreams are ways to interpret life events, and sort through any thoughts or feelings lying in my subconscious. My main question lies in the differences in brain activity between good and bad dreams. Why do you get that physical reaction from a bad nightmare even in your sleep?
Dreams happen during the REM (Rapid Eye Movement) portion of your sleep cycle. The content of dreams can differ from night to night, and even shift during a single night’s sleep. Nightmares are the most common form of disturbed dreaming (Levin & Nielsen, 2007), and are defined as having a high negative emotional content. They can range from mild disturbance to a vivid terror.
No one really knows why certain dreams happen or what causes dreaming in general, but what we can track is the brain activity that occurs during dreams. In waking function, the amygdala is a small, almond shaped part of the brain that is more primarily associated with negative emotions such as fear and anger, although there are links to positive emotion within the amygdala (Blake, 2014). While the fear control function mostly lies on the hypothalamus, the physical expression of that fear during nightmares is closely attributed to the amygdala (Levin & Nielsen, 2007). Specifically, the sympathetic nervous system that activates in times of anxiety and fear. You know that feeling when you’re terrified and your breath shallows, your digestion stops (or quickens in my case), you sweat more, and your heart pounds faster? That is all courtesy of the sympathetic nervous system that lies under autonomic brain activity. There have also been higher rates of arousal documented in close relation to high cortisol and heightened autonomic nervous system activation during nightmares (Paul et. al., 2019). Cortisol is the stress hormone released in distressing situations, often accompanied by the overactivation of the autonomic nervous system. During nightmares where the entire premise is fear and distress, the study by (Paul et. al., 2019) compared nightmares and regular dreams, and the cortisol levels went from 1.96 to 2.10 after the nightmare. it makes sense that a stress hormone and the autonomic system will be put into overdrive due to the fear expression caused by the amygdala.
But what about good dreams? Most of the brain activity associated with good dreams is the release of certain happy hormones. Namely the “cuddle hormone” Oxytocin. It is the hormone most released during good dreams, particularly those containing loved ones, but even interactions with strangers in dreams are facilitated by oxytocin in order to not create stress around social interaction in the dream (Butnariu & Sarac, 2019).
I also recently had an experience where I was finally falling asleep, something that’s very hard for me, and as I felt sleep finally about to take me my body was thrown off of a cliff and I felt as though I was just about to land (and likely die). I jerked awake with an extremely loud gasp, and due to that experience I had to go through the process of falling asleep all over again (I was quite annoyed). The interesting part was that I wasn’t even dreaming yet, the only thing I felt was that physical reaction to who-knows-what. As it turns out, that phenomenon is called a “hypnic jerk” and it is a benign (non harmful) event that happens when the transition from wakefulness to sleep is not as smooth as usual (Cuellar et. al, 2015). The reticular formation is responsible for wakefulness and alertness, and as we fall asleep it passes the torch to the ventrolateral preoptic nucleus that dictates tiredness. When that transition does not happen smoothly, remaining wakeful energy interrupts the sleepiness, causing a hypnic jerk.
Overall, dreaming can be a big part in how the brain sorts information and there are still numerous studies that delve into it’s true purpose and origins. For now, what we have in information on brain and physical activity during dreams.
Works Cited
Butnariu M, Sarac I. Biochemistry of Hormones that Influences Feelings. Ann Pharmacovigil Drug Saf. 2019; 1(1): 1001
Cuellar NG, Whisenant D, Stanton MP. Hypnic Jerks: A Scoping Literature Review. Sleep Medicine Clinics. 2015 Sep;10(3):393-401, xvi. DOI: 10.1016/j.jsmc.2015.05.010. PMID: 26329450.
Paul F, Alpers GW, Reinhard I, Schredl M. Nightmares do result in psychophysiological arousal: A multimeasure ambulatory assessment study. Psychophysiology. 2019; 56:e13366. https://doi-org.proxy.library.emory.edu/10.1111/psyp.13366
Levin, R., & Nielsen, T. A. (2007). Disturbed dreaming, posttraumatic stress disorder, and affect distress: A review and neurocognitive model. Psychological Bulletin, 133(3), 482-528.