Your mind doesn't work the same way at 2am as it does at 2pm.
Under the cover of darkness, negative thoughts have a way of taking over. Cravings you'd shrug off at lunchtime – a cigarette, a carb-heavy binge – suddenly feel a lot harder to resist.
Inhibitions that hold firm all day quietly loosen their grip.
There's a name for this: scientists call it 'Mind After Midnight' – a hypothesis, laid out in a 2022 paper, that the brain doesn't just get sleepy at night. It changes.
Past midnight, negative emotions draw our attention more than positive ones, dangerous ideas grow more appealing, and the usual brakes come off.
According to the researchers behind it, the human body and mind run on a roughly 24-hour cycle that doesn't just decide when we feel tired – it reshapes how we feel, and how we're inclined to act.
In short, at certain hours, our species is inclined to feel and act in certain ways. In the daytime, for instance, molecular levels and brain activity are tuned to wakefulness. But at night, our usual behavior is put to sleep.
From an evolutionary standpoint, this, of course, makes sense. Humans are much more effective at hunting and gathering in the daylight, and while nighttime is great for rest, humans were once at greater risk of becoming the hunted at this time.
According to the researchers, to cope with this increased risk, our attention to negative stimuli is unusually heightened at night.
Where it might once have helped us jump at invisible threats, this hyperfocus on the negative can then feed into 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 fairly good evidence that their brain is not functioning as well as it does during the day," said neurologist Elizabeth Klerman from Harvard University in 2022 when the study was published.
"My plea is for more research to look at that, because their health and safety, as well as that of others, is affected."
The authors of the hypothesis use two examples to illustrate their point. The first example is of a heroin user who successfully manages their cravings during the day but succumbs to their desires at night.
The second is of a college student struggling with insomnia, who begins to feel a sense of hopelessness, loneliness, and despair as the sleepless nights stack up.
Both scenarios can ultimately prove fatal. Suicide and self-harm are very common at night. In fact, some research reports a threefold higher risk of suicide between midnight and 6:00 am compared to any other time of day.
A study in 2020 concluded that nocturnal wakefulness is a suicide risk factor, "possibly through misalignment of circadian rhythms."
"Suicide, previously inconceivable, emerges 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 of the 'Mind After Midnight' hypothesis explain.
Illicit or dangerous substances are also taken more by people at night. In 2020, research at a supervised drug consumption center in Brazil revealed a 4.7-fold greater risk of opioid overdose at night.
Some of these behaviors could be explained by sleep debt or the cover that darkness offers, but there are probably nighttime neurological changes at play, too.
That's a different problem to the one we covered earlier this year, when we looked at why so many people jolt awake around 3am for no obvious reason.
That kind of waking is usually nothing to worry about – humans slept in two separate blocks for most of history, long before electric light convinced us eight unbroken hours was the only normal way to do it.
What the Mind After Midnight hypothesis describes is something else entirely: not a brief stir before drifting back off, but being fully awake for hours on end, at a time when – researchers argue – your brain is actively worse equipped to handle it.
Researchers like Klerman and her colleagues think we need to investigate these factors further to make sure we are protecting those most at risk from nighttime wakefulness.
Related: Experiment Tested Out-of-Body Experiences. Two Reported Seeing Things Scientists Can't Explain.
To date, the authors said no studies have examined how sleep deprivation and circadian timing impact a person's reward processing.
As such, we don't really know how shift workers, such as pilots or doctors, are coping with their unusual sleep routine.
For six hours or so 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.
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