Science Alert reports:

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 might start craving guilty pleasures, like a cigarette or a carb-heavy meal.

Plenty of evidence suggests the human mind functions differently if it is awake at nighttime. Past midnight, negative emotions tend to draw our attention more than positive ones, dangerous ideas grow in appeal and inhibitions fall away.

Some researchers think the human circadian rhythm is heavily involved in these critical changes in function, as they outline in a new paper summarizing the evidence of how brain systems function differently after dark.

Their hypothesis, called ‘Mind After Midnight’, suggests the human body and the human mind follow a natural 24-hour cycle of activity that influences our emotions and behavior.

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 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.

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 hyper-focus 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. [Continue reading…]