In the middle of the night, the world can sometimes feel like a dark place. Under the cover of darkness, negative thoughts have a way of drifting through your mind, and as you lie awake, staring at the ceiling, you may begin to crave guilty pleasures, like a cigarette or a carbohydrate-rich meal.
Lots of evidence suggests that the human brain works differently if it’s awake at night. After midnight, negative emotions tend to attract our attention more than positive, dangerous thoughts grow in attraction and inhibitions fade.
Some researchers believe the human circadian rhythm is deeply involved in these critical changes in function, as they outline in a new paper that summarizes evidence for how brain systems function differently after dark.
Their hypothesis, called “The Mind After Midnight,” proposes that the human body and mind follow a natural 24-hour cycle of activity that influences our emotions and behavior.
In short, at certain hours, our species tends to feel and act in certain ways. In the daytime, for example, molecular levels and brain activity are tuned to wakefulness. But at night, our usual behavior is to sleep.
From an evolutionary point of view, this of course makes sense. Humans are more effective at hunting and gathering in broad daylight, and while the night is great for rest, humans were once more at risk from hunting.
According to the researchers, to deal with this increased risk, our attention to negative stimuli is unusually increased at night. Where it may have helped us jump into invisible threats, this excessive focus on negativity can fuel an altered reward/stimulus system, making a person especially vulnerable to risky behaviors.
Add sleep loss to the equation, and this state of consciousness becomes even more problematic.
“Millions of people are awake in the middle of the night, and there is fairly good evidence that their brains do not function as well as they do during the day,” says neuroscientist Elizabeth Klerman of Harvard University.
“I appeal to more research to look into that, because their health and safety, as well as the health of others, is affected.”
The authors of the new hypothesis use two examples to illustrate their point. The first example is a heroin user who successfully manages his desires by day but gives in to his desires at night.
The second is for a college student who suffers from insomnia, and begins to feel hopeless, lonely and hopeless as his insomnia nights pile up.
Both scenarios can be fatal in the end. Suicide and self-harm are very common at night. In fact, some research suggests the risk of suicide is three times higher between midnight and 6 a.m. than at any other time of the day.
A study in 2020 concluded that nocturnal vigilance is a risk factor for suicide, “possibly through disruption of circadian rhythms.”
“Suicide, previously unimaginable, shows an escape from loneliness and pain, and before the costs of suicide are considered, the student has acquired the means and is ready to act at a time when no one is awake to stop them,” the authors explain, explaining the “midnight mind” hypothesis. “.
Illegal or dangerous substances are used more often at night. In 2020, research conducted at a Supervised Drug Consumption Center in Brazil revealed a 4.7 times greater risk of opioid overdose at night.
Some of these behaviors may be explained by the debt of sleep or the cover provided by darkness, but it is possible that nocturnal neurological changes play a role as well.
Researchers like Klerman and her colleagues believe we need to investigate these factors further to ensure that we protect those most at risk from nocturnal vigilance.
So far, the authors say there are no studies that have examined how sleep deprivation and circadian timing affect a person’s reward processing.
As such, we don’t really know how shift workers, such as pilots or doctors, deal with their unusual sleep routine.
For six hours or so a day, we don’t know much about how the human brain works. Whether asleep or awake, the mind after midnight is a mystery.
The study was published in Frontiers in Network Psychology.
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