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Study reveals brain's "blue spot" as key player in sleep cycles
Last reviewed: 03.07.2025
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Scientists from the University of Lausanne have for the first time identified the key role of a brain region called the locus coeruleus (LC) in sleep organization and sleep disorders. The study showed that the LC plays an important role in the transitions between sleep phases (NREM and REM), ensuring "unconscious alertness" during sleep. The discovery sheds light on the mechanisms of sleep disruption under stress and offers new approaches to treatment.
Main discoveries
LC as a "gateway" between NREM and REM sleep
- The LC, previously known as the production center for norepinephrine, a hormone responsible for stress response and wakefulness, has been shown to be a key element in regulating the sleep cycle.
- Under normal conditions, LC activity fluctuates every 50 seconds, allowing the body to:
- At peak activity levels: ensure alertness and readiness to awaken.
- In the waning phases: initiate the transition to REM sleep, characterized by active brain activity.
New Structural Organization of Sleep
Researchers have shown that the sleep cycle consists of previously unknown "structural units," in which:- Peaks of LC activity provide a state of semi-wakefulness at the subcortical level of the brain.
- Declines in activity create the conditions for the transition to REM sleep.
The Impact of Stress on LC and Sleep
- Stress experienced during the day increases LC activity during sleep, resulting in:
- Delayed onset of REM sleep.
- Fragmentation of NREM sleep due to frequent awakenings.
- This is particularly important for understanding the link between sleep disturbances and mental disorders such as anxiety.
- Stress experienced during the day increases LC activity during sleep, resulting in:
LC functions during sleep
NREM sleep
- Characterized by deep stages of sleep, necessary for the body's recovery.
- LC controls the transition from NREM to REM sleep, and LC activity should be low.
REM sleep
- Associated with intense brain activity and dreams.
- Norepinephrine secreted by the LC prevents too frequent awakening, but when it is produced in excess (for example, due to stress), REM sleep is delayed.
Practical significance
Diagnosis and treatment of sleep disorders
- LC can be used as a biomarker to assess and correct sleep cycles.
- The study opens up possibilities for developing new treatments for sleep disorders associated with anxiety and stress.
Clinical applications
- Research has begun with the Lausanne University Hospital (CHUV) to confirm the applicability of the mechanisms identified in mice to human sleep.
Evolutionary aspects of sleep
- Some reptiles that do not have a clear distinction between NREM and REM have been found to have sleep cycles lasting 50 seconds, indicating possible ancient analogues of LC activity.
Conclusions
The study of LC as a "switch" between sleep stages provides new insights into sleep organization and disruption. This discovery not only helps us understand how stress affects sleep, but also suggests ways to develop more effective treatments, from monitoring to adjusting the sleep cycle, using LC as a therapeutic target.
The study was published in the journal Nature Neuroscience.