Research conducted by the Perelman School of Medicine has shed light on the negative impact of stress on sleep and suggested potential treatments for sleep disorders. The researchers delve into these compelling findings in detail.
Shinjae Chung, a PhD holder at Penn Medicine, explains the detrimental effects of poor sleep quality. "When you have a bad night of sleep, you notice that your memory isn’t as good as it normally is, or your emotions are all over the place—but a bad night of sleep interrupts so many other processes throughout your body," he says. He further notes that "this is even more heightened in individuals with stress-related sleep disorders."
A typical sleep cycle lasts ninety minutes and comprises three stages of non-rapid eye movement (NREM) sleep and one stage of rapid eye movement (REM) sleep. The initial two stages of NREM sleep involve a general slowdown - brain waves and breathing slow down, and temperature decreases. Simultaneously, the brain processes and consolidates memory. In the third stage of NREM sleep, growth hormone is produced by the body. During REM sleep, memories are formed, emotions are managed, and overall development occurs; this phase is also associated with dreaming.
The researchers from the Perelman School of Medicine conducted an intriguing study on mice to observe these stages of sleep. According to a news release from Penn Medicine: "In the study, researchers noticed that glutamatergic neurons (VGLUT2) are periodically activated during NREM sleep." VGLUT2 was primarily activated during wakefulness. Suspecting VGLUT2 as a cause for microarousals during sleep, they stimulated these neurons during slumber and found that it indeed increased wakefulness.
Chung reveals an interesting correlation between these neurons and stress: exposure to stressors reduced sleep quality while increasing VGLUT2 production during NREM sleep. However, when VGLUT2 production was curtailed, NREM sleep was extended and microarousals decreased. Chung says, "It’s crucial to understand the biology driving the brain activity in these crucial stages of sleep, and how stimuli like stress can disrupt it, so that we might someday develop therapies to help individuals have more restful sleep that allows their brain to complete these important processes."
The study's findings suggest that suppressing VGLUT2 neurons could potentially improve sleep disorders. Jennifer Smith, the first author of the study and a graduate researcher in Chung’s lab, supports this notion: "The glutamatergic neurons in the hypothalamus give us a promising target for developing treatments for stress-related sleep disorders. Being able to reduce interruptions during the important stages of non-REM sleep by suppressing VGLUT2 activity would be groundbreaking for individuals struggling with disrupted sleep from disorders like insomnia or PTSD," according to a news release from Penn Medicine.
