Things that don't bother you so much during the day may become more and more negative in your thoughts in the middle of the night, and you may even be more likely to be impulsive and eat high-calorie foods? Researchers proposed the "Mind After Midnight" hypothesis, which believes that when people continue to be awake during the physiological night, circadian rhythm and lack of sleep may jointly affect mood, reward processing, and executive functions, making people more likely to fall into negative thinking or impulsive behavior.
According to a recent report by "Science Alert", this hypothesis was proposed by researchers from the University of Arizona, the University of Pennsylvania, and Harvard Medical School/Massachusetts General Hospital in the United States in 2022. The relevant paper was published in the journal "Frontiers in Network Physiology". After sorting out existing neuroscience and behavioral research, the research team proposed the "post-midnight brain" hypothesis, which attempts to explain why people may have different thinking and behavior patterns from those during the day when they are awake during the physiological night.
Researchers point out that a person's circadian rhythm changes wakefulness, cognitive abilities and mood regulation over time. During the physiological night, lack of sleep and changes in the biological clock may work together, causing people to increase their attention to negative stimuli, decrease their ability to regulate emotions, and executive functions responsible for judgment, impulse suppression, and risk assessment may also be affected.
According to this hypothesis, when you are awake at night, negative emotions, attention bias, reward processing and prefrontal lobe control may influence each other, making worries that can be temporarily put aside during the day become more difficult to escape in the early morning; high-calorie food, alcohol or other behaviors with immediate reward effects may also appear more attractive. The research team emphasized that this is a theoretical framework used to explain nighttime behavioral changes, and is not a single causal mechanism that has been established.
The brain may have changed its mode late at night
Existing studies cited in the paper also found that the risks of some nighttime behaviors may be increased. For example, after correcting for the proportion of the population awake at different times, the risk of suicide from midnight to 6 a.m. is about three times that of other times; another study found that the risk of opioid overdose at night is about 4.7 times that of the day. However, these data come from existing studies and cannot directly prove that the "post-midnight brain" hypothesis is responsible for the increased risk.
The original paper points out that follow-up research still needs to further distinguish the effects of sleep deprivation and the circadian clock itself in order to clarify how the two jointly change mood, cognition and behavior at night. For shift workers, this hypothesis also provides new research directions, including exploring whether doctors, pilots, and other people who often stay awake at night are more susceptible to these physiological and psychological changes.
