2023-11-02 17:00:07
Going all night without sleep can have a beneficial effect on depressive states. A team of researchers from the Northwestern University (USA) has studied the well-known phenomenon of mood elevation associated with sleep deprivation, an effect by which a specific decrease in sleep causes a change in the mood of mice.
According to their results, the animals became more hyperactive and hypersexual for a few hours. Furthermore, the occasional lack of sleep had an antidepressant effect that lasted for a few days and was explained by an increase in the release of dopamine. The results are published in the journal ‘Neuron‘.
Most people who have spent an all-nighter are familiar with that feeling of “tiredness and tension». Although the body is physically exhausted, the brain feels happy, a little crazy and almost dizzy.
Neurobiologists at Northwestern University are the first to discover what causes this drunk effect.
In their study, the researchers induced mild, acute sleep deprivation in mice and then examined their behaviors and brain activity. Not only did it increase dopamine release during the period of acute sleep loss, but it also improved synaptic plasticity, literally rewiring the brain to maintain a happy mood for days to come.
These new findings could help better understand how moods change naturally. It could also lead to a more complete understanding of how fast-acting antidepressants (such as ketamine) work and help researchers identify previously unknown targets for new antidepressant drugs.
“Chronic sleep loss is well studied and its detrimental effects are widely documented,” explains Yevgenia Kozorovitskiy, expert in neuroplasticity. “However, brief sleep loss, such as the equivalent of a student pulling an all-nighter before an exam, is less understood. We discovered that lack of sleep induces a powerful antidepressant effect and rewires the brain. “This is an important reminder of how our casual activities, like a sleepless night, can fundamentally alter the brain in just a few hours.”
Scientists have long known that acute disturbances during sleep are associated with altered mental states and behaviors. Disturbances of sleep and circadian rhythms in patients, for example, can trigger mania or occasionally reverse depressive episodes.
Hyperactive and hypersexual
To explore these mechanisms, Kozorovitskiy and his team developed a new experiment to induce acute sleep loss in mice that had no genetic predispositions related to human mood disorders. The experimental setup needed to be gentle enough to avoid causing substantial stress to the animals, but uncomfortable enough to prevent the animals from falling asleep. After a sleepless night, the animals’ behavior changed and they became more aggressive, hyperactive and hypersexual, compared to controls who experienced a typical night’s sleep.
Using optical and genetically encoded tools, the researchers measured the activity of neurons in dopamine, which are responsible for the brain’s reward response. And they found that activity was greater in the animals during the brief period of sleep loss.
“We were curious to know which specific regions of the brain were responsible for behavioral changes,” Kozorovitskiy said. “We wanted to know if this was a large transmission signal that affected the entire brain or if it was something more specialized.”
The scientists examined four brain regions responsible for dopamine release: the prefrontal cortex, nucleus accumbens, hypothalamus, and dorsal striatum. After monitoring dopamine release in these areas after acute sleep loss, they found that three of the four areas (the prefrontal cortex, nucleus accumbens, and hypothalamus) were involved.
But the team wanted to limit the results even further, so they systematically silenced dopamine reactions. The antidepressant effect disappeared only when the researchers silenced the dopamine response in the medial prefrontal cortex. In contrast, the nucleus accumbens and hypothalamus seemed to be more involved in hyperactive behaviors, but were less connected to the antidepressant effect.
“The antidepressant effect persisted except when we silenced dopamine input to the prefrontal cortex,” explains Kozorovitskiy. That means that the prefrontal cortex It is a clinically relevant area when seeking therapeutic objectives. But it also reinforces the idea that’s been building in the field recently: dopamine neurons play very important but very different functions in the brain. “They’re not just this monolithic population that just predicts rewards.”
While most behaviors (such as hyperactivity and increased sexuality) disappeared within a few hours of acute sleep loss, the antidepressant effect persisted for a few days. This suggested that synaptic plasticity in the prefrontal cortex could be enhanced.
The antidepressant effect is temporary and we know the importance of getting a good night’s sleep. I would say it’s better to go to the gym or take a nice walk
Yevgenia Kozorovitskiy
University of Northwestern
When they examined individual neurons, they discovered just that. Neurons in the prefrontal cortex formed small protuberances called dendritic spines, highly plastic features that change in response to brain activity. When they used a genetically encoded tool to dismantle synapses, they reversed the antidepressant effect.
While researchers don’t fully understand why lack of sleep causes this effect on the brain, Kozorovitskiy suspects that evolution is at play.
Ahora bien, Kozorovitskiy warns people not to start staying up all night to lighten their mood.
“The antidepressant effect is temporary and we know the importance of getting a good night’s sleep,” he warns. I would say it’s better to go to the gym or take a nice walk. “This new knowledge is most important when it comes to finding a person the right antidepressant.”
In this sense, Eduard Vieta, scientific director of the Biomedical Research Center in Mental Health Network (CIBERSAM), states Science Media Centre that “sleep deprivation is not commonly used for depression because its antidepressant effects are transient and mood returns to its previous state upon returning to sleep, so its use is not recommended. However, the study explains the mechanisms underlying this effect and could open the door to other treatments.
#Lack #sleep #therapy #depression