Researchers call for new studies to learn how our brains change when we’re awake after midnight

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If you’ve ever stayed up late reacting angrily to Twitter posts, eating an entire pint of ice cream from the container, drinking another bottle of wine, or just feeling miserable, you may identify with the Mind After Midnight hypothesis.

The hypothesis, which was described in a recent article in Boundaries in Network Psychologysuggests that when people are awake during the biological circadian night — past midnight for most people — there are neurophysiological changes in the brain that alter the way we interact with the world, particularly actions related to reward processing, impulse control, and information processing.

These changes make you more likely to view the world negatively, engage in harmful behavior, and make impulsive decisions (including decisions related to addictive behaviors such as gambling and substance abuse) without fully considering the consequences.

“The basic idea is that from a global, high-level evolutionary standpoint, your internal biological circadian clock is tuned to processes that promote sleep, not being awake, after midnight,” says Elizabeth B. Klerman, MD, Ph.D., a researcher. researcher in the Department of Neurology at Massachusetts General Hospital, professor of neurology at Harvard Medical School, and the paper’s senior author.

Klerman describes the hypothesis as a call to researchers to conduct new studies to better understand how these circadian differences affect behavior, decision-making and work performance at night — and identify strategies that can help people cope.

The findings could have far-reaching implications for individuals who need to be awake at night to work, including pilots, health professionals, police officers and military personnel. Research may also lead to new strategies to reduce violent crime, substance use disorders, suicides and other harmful behaviors.

“There are millions of people who are up in the middle of the night, and there’s pretty good evidence that their brains don’t function as well as they do during the day,” Klerman says. “My plea is for more research to look at that, as their health and safety, as well as that of others, is being compromised.”

Bad things happen in the dark

Previous research has shown that people are more at risk for harmful behaviors, such as suicide, violent crime and substance use at night.

For example, Michael L. Perlis, Ph.D., an associate professor of psychology at UPenn’s Perelman School of Medicine and co-author of the Mind After Midnight hypothesis, found that if you adjust for the number of people awake at each At any given time, the risk of suicide is statistically greater during the nighttime hours.

Murders and violent crimes are also more common at night, as are the risks of illegal or inappropriate use of substances such as cannabis, alcohol and opioids.

Our nighttime food choices are also often unhealthy, as we pursue more carbohydrates, lipids and processed foods and often consume more calories than we need.

So how come all this bad behavior comes out at night?

There are a few obvious answers: For example, it is much easier to commit a crime under the cover of darkness, and there are fewer people around and up at night to help us control our behavior to keep. But it is likely that there is also a biological basis.

Klerman explains that the circadian influence on neural activity in our brains changes over the course of 24 hours, leading to differences in the way we process and respond to the world.

For example, positive affect—the tendency to see information in a positive light—is at its highest point during the morning, when circadian influences are aligned with wakefulness, and at its lowest point during the night, when circadian influences are aligned with sleep.

At the same time, negative affect tends to see information in a negative or threatening light at night.

Your body also naturally produces more dopamine at night, which can alter your reward and motivation system and increase the likelihood of risky behavior.

This biased interpretation of information is then routed to the parts of the brain responsible for decision-making, which normally work to manage negative emotional distractions and focus on goal-directed behavior.

But these parts of the brain are also subject to circadian-influenced changes that can affect decision-making, functioning and prioritization.

Suddenly your world view narrows and becomes more negative, you start making bad decisions, and the mental map you make of the world around you may no longer match reality.

The result? You could end up drinking too much, missing a crucial patient diagnosis, crashing an oil tanker into some rocks, or worse.

Klerman experienced some of these feelings firsthand as she struggled to fall asleep after severe jet lag during a trip to Japan.

“While part of my brain knew I would eventually fall asleep, laying there watching the clock tick, tick, tick – I was beside myself,” she recalls.

“Then I thought, ‘What if I was a drug addict? I’d try to get drugs now.’ I later realized that this can also be relevant when it comes to suicidal tendencies, or substance abuse or other impulse disorders, gambling or other addictive behaviors. How can I prove that?”

Putting the Hypothesis to the Test

The need for proof is central here. It’s important to note that Mind After Midnight is still a hypothesis – one that needs to be validated through carefully crafted research studies.

In an ironic twist, the best way to collect this data without the confounding effects of sleep loss requires researchers and study personnel to be awake and work after midnight, for example, by taking fMRI images of study participants whose sleep cycles have been carefully modified for nighttime wakefulness. or running other protocols.

“Most researchers don’t want to be paged in the middle of the night. Most research assistants and technicians don’t want to be up in the middle of the night,” admits Klerman.

“But we have millions of people who need to be up at night or involuntarily awake at night. Some of us will need to be inconvenienced so we can better prepare them, treat them, or do what we can to help.”

Light in your bedroom is not good for your health

More information:
Andrew S. Tubbs et al, The Mind After Midnight: Nocturnal Wakefulness, Behavioral Disregulation, and Psychopathology, Limits in Network Physiology (2022). DOI: 10.3389/fnetp.2021.830338

Provided by Massachusetts General Hospital

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