New research shows that short-term sleep loss not only affects our brains, but also our emotions.
We all know that sleep is important for our health and well-being. After all, chronic sleep loss has already been studied quite well, and its harmful effects have been extensively mapped out. But what impact does one all-nighter have, for example to study for an exam or to party with friends? To find out, researchers held the Northwestern University mice woke up for a long time and looked at what that did in their brains.
It shows that sleep loss produces a powerful antidepressant effect and rewires the brain. Involved researcher Yevgenia Kozorovitskiy. “This just goes to show how our seemingly innocent activities, like a sleepless night, can fundamentally change the brain in just a few hours.”
Antidepressief effect
The researchers drew this conclusion after keeping mice awake for twelve hours. Mice are normally only awake for about nine hours a day, making this a major disruption to their sleep cycle. The researchers saw that sleep deprivation stimulated a specific brain area involved in reward and motivation. Dopamine is produced in this area; a neurotransmitter that plays a role in pleasure, mood and addiction. Remarkably, sleep deprivation therefore had an antidepressant effect in the sleep-deprived mice. They were less anxious and depressed than the mice that had slept normally. In addition, they were more interested in new objects and rewards, such as sugar water.
We also recognize this positive effect in people, the researchers say. After a night of very little sleep you can feel physically very tired, but still very cheerful. A bit giggly even. This is not just because there is more dopamine release during a period of acute sleep loss, the researchers discovered. Certain connections in the brain are also strengthened. In this way, the brain is, as it were, rewired to maintain that vibrant mood for a little longer.
On and off
“We were curious about which specific areas of the brain were responsible for those behavioral changes,” Kozorovitskiy said. “Was this a big, broad signal that affected the whole brain or something more specialized?” To investigate this, the researchers temporarily switched off the prefrontal cortex of the mice. This part of the brain is involved in higher cognitive functions, such as planning, decision-making and self-control. By temporarily switching off that brain area, the antidepressant effect of the acute sleep loss suddenly disappeared. “This not only means that the prefrontal cortex is interesting for future treatments. It also reinforces the idea that dopamine neurons play very important, but also very different roles in the brain than previously thought. It is not just a substance that predicts rewards.”
Dopamine
We quickly associate the neurotransmitter dopamine with positive events. Good food, sports and other activities that stimulate the ‘happiness hormones’. It therefore sounds somewhat contradictory that you get dopamine from sleep deprivation. Yet that is not very surprising. Dopamine helps you stay alert and motivated, despite fatigue. In this way the brain can adapt to a stressful situation. However, this mechanism also has a downside. It can lead to addiction, impulsivity and mood swings in the long term. That is why it is important to get enough and regular sleep so that your dopamine levels remain balanced.
The researchers therefore emphasize that their findings do not mean that short-term sleep loss is a good way to treat depression. Rather, they warn that disrupting the natural sleep cycle can have long-term detrimental effects on brain health and well-being. They hope that their study can lead to new insights and strategies to improve mood and combat depression, without neglecting sleep.
While an all-nighter has a temporary antidepressant effect, missing sleep has a completely different effect in the long term. “We suddenly see the world around us through very negative glasses,” Ben Simon previously explained Scientias.nl. “As a result, someone also experiences the intentions of others more negatively, which means that he or she is less likely to be kind or helpful. We are starting to see more and more evidence that sleep deprivation leads to ‘antisocial’ behavior,” said Simon. “Insufficient sleep has already been associated with an increase in loneliness, reduced empathy, a greater desire to be alone and now with reduced helpfulness. Sleep is critical for many basic life support systems, both physical and mental.”
