Staying Up Past Midnight Might Make Us More Impulsive and Cynical

In 2022, a team of psychologists suggested burning the midnight oil could lead to changes in the brain associated with hazardous behaviors and harmful health outcomes. In essence, it might not just be how long or how well you sleep but when you squeeze in shut-eye that matters.

Writing in the journal Frontiers in Network Psychology, the researchers outlined the “Mind After Midnight” hypothesis. The theory links staying up into the early hours to a series of neurophysiological changes that influence our behaviour, making us more impulsive, more cynical, and more likely to participate in harmful activities.

The Link Between Bedtime and Mental Health

There is some evidence for this reasoning. Research has found that the number of violent crime and homicides increase after dark, as does the risk of suicide and suicidal thinking. On a less extreme level, data suggests we are more at risk of obesity and more likely to indulge in unhealthy foods if we eat at night. A caveat: these studies don’t always separate nocturnal wakefulness from sleep loss. It is also worth noting that there may be other factors driving these behaviors, such as darkness providing a better cover for crime than daylight.

When the study was first published, lead author Elizabeth B. Klerman, Professor of Neurology at Harvard Medical School, called for more research into the phenomenon.

“My plea is for more research to look at that, because their health and safety, as well as that of others, is affected,” she said in a press release.

More recently, researchers examining the link between bedtimes and mental health have advised turning in before 1 a.m. — even if you are a self-described “night owl.”

Brain Function After Midnight

The hypothesis is based on the idea that our brains are influenced by the circadian clock, which can alter the way we think and act over a 24-hour time period. The result is that we may be more cheerful in the morning, when we are designed to feel awake, and more gloomy at night, when our body is preparing for sleep.

The circadian clock can and does vary on an individual-to-individual basis, with some of us running a little ahead of schedule (morning larks) and some of us a little behind (night owls). But at a population level, most people in the U.S. can expect to feel their most awake between 10 a.m. and 8 p.m. and their least awake around 3 a.m.

According to Klerman and co, negative bias could result in poor decision-making. This could be exacerbated by a surge in dopamine that impacts the reward and motivation system, increasing the possibility of risky behavior.

Bed Before 1 A.M.

Research has shown that general mood and well-being levels tend to be lower when the circadian rhythm is misaligned — a pattern seen in shift workers. Meanwhile, a paper published in Psychiatry Research detected a peak in “negative affect” (or low mood) at night, which the researchers suggest may help explain the link between depression and insomnia.

More recently, a 2024 study in Psychiatry Research found that those who go to bed early display better mental health — regardless of whether or not they consider themselves a morning lark or night owl. The researchers came to this conclusion after comparing sleeping patterns to rates of depression and anxiety in over 70,000 middle- and older-aged adults.

They advised, “For healthy aging, it is recommended that individuals initiate their sleep before [1 a.m.], regardless of their chronobiological preferences.

Perhaps most intriguingly, the researchers of the paper found that it was not morning larks out of step with their preferences that experienced the worst outcomes, but night owls who were apparently in line with theirs.

"If I had to hazard a guess, morning people who are up late are quite cognizant of the fact that their brain isn't working quite right, so they may put off making bad decisions," senior author Jamie Zeitzer, professor of psychiatry and behavioural sciences at Stanford Medicine, said in a statement.

"Meanwhile, the evening person who is up late thinks, 'I'm feeling great. This is a great decision I'm making at 3 o'clock in the morning."

This article is not offering medical advice and should be used for informational purposes only.

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