In the middle of the night, the world can sometimes feel like a dark place. Under the cloak of darkness, negative thoughts have a way of floating through your mind, and as you lie awake, staring at the ceiling, you may start to crave guilty pleasures, like a cigarette or a high-carb meal.
Much evidence suggests that the human mind works differently if it is awake at night. After midnight, negative emotions tend to get our attention more than positive ones, dangerous ideas become attractive, and inhibitions fade.
Some researchers believe that the human circadian rhythm is heavily involved in these critical changes in function, as they describe in a new paper that summarizes evidence for how brain systems work differently after dark.
His hypothesis, called ‘Mind After Midnight’, suggests that the human body and the human mind follow a natural 24-hour cycle of activity that influences our emotions and behaviour.
In short, at certain times, our species is inclined to feel and act in certain ways. During the day, for example, molecular levels and brain activity adjust to wakefulness. But at night, our usual behavior is to sleep.
From an evolutionary point of view this, of course, makes sense. Humans are much more effective at hunting and gathering during the day, and while the night is great for resting, humans were once at a higher risk of being hunted.
According to the researchers, to cope with this increased risk, our attention to negative stimuli increases unusually at night. If it ever helped us attack invisible threats, this hyperfocus on the negative can fuel an altered reward/motivation system, making a person particularly prone to risky behaviors.
Add sleep loss to the equation, and this state of consciousness only becomes more problematic.
“There are millions of people who are awake in the middle of the night, and there’s pretty good evidence that their brain doesn’t work as well as it does during the day,” says neurologist Elizabeth Klerman of Harvard University.
“My request is that more research be done to look into that, because your health and safety, as well as that of others, is affected.”
The authors of the new hypothesis use two examples to illustrate their point. The first example is of a heroin user who successfully manages his cravings during the day but succumbs to his cravings at night.
The second is from a college student struggling with insomnia, who begins to feel a sense of hopelessness, loneliness, and despair as the sleepless nights pile up.
Both scenarios can ultimately prove fatal. Suicide and self-harm are very common at night. In fact, some research reports a three times higher risk of suicide between midnight and 6:00 am compared to any other time of day.
A 2020 study concluded that nighttime wakefulness is a risk factor for suicide, “possibly due to misalignment of circadian rhythms.”
Suicide, previously inconceivable, arises as an escape from loneliness and pain, and before the costs of suicide are considered, the student has acquired the means and is prepared to act at a time when no one is awake to stop them. “, the authors explain the hypothesis of the ‘mind after midnight’.
People also take more illicit or dangerous substances at night. In 2020, research at a supervised drug abuse center in Brazil revealed a 4.7-fold increased risk of opioid overdose at night.
Some of these behaviors could be explained by lack of sleep or the cover offered by darkness, but nocturnal neurological changes are probably also at play.
Researchers like Klerman and colleagues believe we need to investigate these factors further to make sure we’re protecting people most at risk from nighttime wakefulness.
To date, the authors say, no study has examined how sleep deprivation and circadian rhythm affect a person’s reward processing.
As such, we don’t really know how shift workers like pilots or doctors are coping with their unusual sleep routine.
For about six hours a day, we know surprisingly little 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.