Researchers from the University of Lausanne have found that stress affects the locus coeruleus, an area of the brain that regulates the transition between the phases of REM and REM sleep. This leads to sleep fragmentation and frequent awakenings. The study is published in the journal Nature Neuroscience. The blue spot is responsible for the production of norepinephrine, a hormone that regulates the stress response and maintains wakefulness. However, new findings have shown that this area of the brain also plays an important role in controlling sleep cycles. Scientists found that the activity of the locus coeruleus fluctuates every 50 seconds, creating a kind of “clock” that regulates transitions between sleep stages. Daytime stress increases the activity of the spot by increasing norepinephrine levels. This leads to disturbances: the onset of the REM phase of sleep is delayed and slow-wave sleep begins to interrupt, causing frequent awakenings. The results of the study open the way to the creation of new methods of diagnosis and treatment. The blue spot could become a biomarker for monitoring and correcting sleep cycles, especially in patients with anxiety disorders and other disorders. The work also provides a better understanding of sleep evolution. Some reptiles, for example, show similar cyclic fluctuations in brain activity, indicating the ancient origin of this brain region.