- A new review suggests the brain is not “designed” to be active after midnight.
- Physiological changes at night, such as neuronal activity, are linked with behavior disruption.
- Circadian rhythms also play a key role in nocturnal brain function.
- Still, many people may find they’re more productive or creative at night, while others may have jobs that require them to work at night.
- Further research is needed to explore the effects of nighttime activity on mental and physical health.
Most people have been tempted to stay up late at some point in their lives. Others may have to work late, often past midnight, due to the nature of their job.
But a new research review, recently published in the journal Frontiers in Network Psychology, suggests that staying awake past midnight may have implications that stem beyond needing an extra cup of coffee the next day. In fact, the study authors suggest that the mind simply isn’t “designed” to be awake into the wee hours of the night.
While prior studies have explored the effects of sleep deprivation on cognition, the new research focuses more specifically on what happens to the human brain when it’s awake past midnight.
The resulting “Mind After Midnight” hypothesis states that the mind isn’t set up to operate as it does in the daytime, and as a result, we’re more likely to make impulsive and even “risky” decisions.
In the new review, researchers analyzed a large number of studies investigating the effects of nocturnal behavior on the mind and how the body’s circadian rhythm might influence brain function.
The paper revealed that numerous physiological activities occur in the brain (when awake during nighttime) to contribute to poor cognition. The authors highlighted that being awake during the night is associated with an increased risk of:
- suicide and self-harm
- engaging in violent behaviors
- use of alcohol and illicit substances
- higher food intake
According to the researchers, our molecular levels, neuronal activities, and responsivity are attuned to our “usual behavior” of wakefulness during the day. At nighttime, however, these same parameters are attuned to the “usual behavior of sleep.”
“If we are awake at these times, neurophysiology is prone to foster behavioral dysregulation, especially when these time-of-day effects are combined with sleep loss or disruption,” the study authors wrote.
Despite these findings, experts say that other factors may play a role.
“Cognition and mood are affected by length of time awake, prior sleep history — including insufficient sleep — and circadian rhythms,” study co-author Dr. Elizabeth B Klerman, professor of neurology at Massachusetts General Hospital and the Division of Sleep Medicine at Harvard Medical School in Boston, told Healthline.
In addition, insufficient sleep “prevents neurons from working their best because they haven’t had time to recover, and this deficit applies both during nocturnal wakefulness and the following day,” explained study co-author Dr. Andrew Tubbs, a researcher in the Sleep and Health Research Program at the University of Arizona.
“Circadian rhythms promote wakefulness (and cognition) during the day and then impede/reduce wakefulness (and cognition) at night to promote sleep,” Tubbs said.
“The problem with nocturnal wakefulness is that your neurons are tired from insufficient sleep, and now your circadian rhythms are [also] working to reduce cognition and wakefulness. This dangerous combination is what drives the ‘Mind after Midnight.’”
The body has four different rhythms that help it function, one of which is circadian. Our circadian rhythms essentially tell us when to wake up and wind down.
“The human body’s circadian rhythm [is] essentially the control center for our sleep-wake cycle,” Dee O’Neill, a licensed professional counselor in Texas specializing in brain science, told Healthline.
Various factors can impact circadian rhythm, such as blue light emitted from screens.
“In our modern lifestyles, we tend to be overly exposed to light [for] more hours of the day than our evolutionary brain likely needs,” O’Neill added.
Although most humans experience a similar circadian rhythm, it can differ between individuals.
“Teenagers tend to experience a natural delay in their circadian rhythms during adolescence, which is why they have no trouble staying up until midnight and then struggle to get up at 7 am for school,” Tubbs explained.
In addition, it’s thought there are four chronotypes, or different circadian types, that are influenced by everything from genetics and environment to sex and age.
These chronotypes “play into whether you are more or less affected by the time of day issues,” said Sara Mednick, PhD, professor of cognitive sciences at the School of Social Sciences at the University of California Irvine, and author of “The Hidden Power of the Downstate.”
Many people find they’re more productive or creative at night. For these “night owls,” staying awake past midnight may not have a negative effect.
“[The] ‘Mind After Midnight’ hypothesis suggests by name that being awake after midnight isn’t a good thing,” said Dr. David Rabin, PhD, a neuroscientist, board certified psychiatrist, and co-founder of Apollo Neuro, a wearable device for stress relief.
“However, much of humanity’s most interesting and impactful creative developments have occurred because of individuals’ choices to intentionally stay awake and ponder after midnight.”
Indeed, there are some older studies that may support this concept. For example, a 2009 study found that “more intelligent individuals are more likely to be nocturnal,” while a 2007 study associated night owls with more divergent and creative thinking.
And when it comes to nocturnal brain function, it’s worth considering howlong a person has been awake prior to the clock striking midnight.
“Being awake is a highly energy-depleting process,” Mednick said.“By the end of the day, the particular place most vulnerable to energy depletion is the frontal lobe. This is [the] executive function area, where we make our big decisions about what’s good for us [and] how we should be reacting to the world.”
Energy depletion resulting from sleep deprivation due to being awake for an extended period of time could therefore encourage the brain to engage in activities based on emotion and short-term reward, rather than measured reasoning.
Many people have to work past midnight and even overnight due to the nature of their jobs.
According to the U.S. Centers for Disease Control and Prevention (CDC), around
“We are creatures of habit,” Mednick said, “The more consistent you can be between workdays and non-workdays [is] really important.”
Demonstrating the importance of sleep-wake consistency, a
“The recommendation is for 8 hours of sleep for adults; people can choose in which hours of the day to obtain it,” Klerman said. “Consolidated sleep is better than multiple shorter sleep episodes.”
That said, switching from sleeping at night to during the day isn’t quite so straightforward.
“Your circadian rhythm isn’t really set up to have deep sleep during the day,” Mednick said. “Even if people use blackout curtains and stay in bed for a certain amount of time, it is much harder to achieve the same sort of consolidated sleep that sleeping during the night naturally brings you.”
“Most shift workers are not able to realign their circadian system so that it is aligned with the work schedule rather than the light-dark cycle,” Klerman added.
Tips for better daytime sleep
If you work at night and do have to sleep during the day, Mednick recommended a few approaches to help the brain transition into rest mode so you can sleep better:
- block out as much sunlight as possible
- sleep in a cool room
- wear blue light-reducing glasses while working
- exercise at least 3 hours before sleep
- regulate your eating patterns
The new review paper provides interesting insight into staying awake past midnight and the influence of circadian rhythm on cognitive function. However, more research into the area is still needed.
“The [idea] that [intentionally] staying awake after midnight leads to poor mental health, I would say there is little evidence for,” Rabin said.
To that end, the researchers also noted evidence gaps in some areas.
“The biggest surprise for me was just how little data there are on what people do in the middle of the night,” Tubbs said.
“We combed through study after study looking at the timing of suicide, violent crime, drug use, and other maladaptive behaviors, and found only a handful that tracked these outcomes during the night. Hopefully, our review will encourage other scientists to look at what kinds of behaviors are happening in the middle of the night.”