It's 3 a.m. and your worried brain won't let you go back to sleep. Here's why (2024)

This feature is part of a National Post series by health reporter Sharon Kirkey on what is keeping us up at night. In the series, Kirkey talks to sleep scientists and brain researchers to explore our obsession with sleep, the seeming lack of it and how we can rest easier.

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People tend to slip into a negative place when nature intends them to be asleep. It can be hard to shake the over-thinking, worrying or ruminating, partly because of nocturnal changes in the brain.

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“When I wake at 3 a.m. or so, I’m prone to picking on myself,” clinical psychologist Greg Murray wrote for The Conversation. “And I know I’m not the only one who does this.” Clearly not: The piece, published in 2021, has garnered a cumulative 1.3 million reads.

Thoughts can get trapped in “barbed-wire thinking” when people wake at ungodly hours and can’t get back to sleep, Murray, an expert in circadian rhythms and mood disorders, wrote. At this point in the normal sleep-wake cycle, positive affect — the propensity to feel cheery, enthusiastic or other happy emotions — is at its lowest, while negative affect — sadness, fear, anger, guilt — is at a peak and our risk-reward calculations are warped.

“There isn’t strong data on it, but, theoretically, we expect humans to be prone to negative emotions in the dark, because the dark is evolutionarily threatening to a species designed to see in the daytime,” Murray, director of the Centre for Mental Health and Brain Sciences at Swinburne University of Technology in Melbourne, said in an email to the National Post. “Nighttime isn’t scary for bats, but I presume daytime is.”

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Positive mood, meanwhile, is associated with rewards, or at least the anticipation for rewards. At night, when we’re tired, we can’t process information well and “there isn’t much action in the domain of social rewards” — everyone else is sleeping, after all — humans subconsciously assume rewards are off the table, Murray said.

Nighttime isn't scary for bats, but I presume daytime is

Greg Murray, Swinburne University of Technology, Melbourne

A negative mood can therefore dominate if we’re awake at night and unwanted thoughts are then amplified by our brain state after midnight, Murray said, nodding to the “mind after midnight” hypothesis, which theorizes that people are more likely to think irrationally and behave impulsively between midnight and 6 a.m.

Although it’s not entirely clear what’s happening in the brain, being awake when positive affect is slumping and negative mood is peaking can lead to “depressive, anxious and/or paranoid thinking,” according the experts who crafted the hypothesis.

“You get this perfect storm of not being your best self,” Michael Grandner, director of the University of Arizona’s sleep and health research program told a Canadian Sleep Research Consortium virtual webinar this year. “You’re cognitively and affectively dysregulated, which is why nothing good happens between two and five in the morning.”

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Nighttime awakenings are common. One survey of 2,000 American adults found only 10 per cent reported never waking in the middle of the night in the month prior. Sixteen per cent reported it happened more than 20 nights.

“Some of it is based on temperament, said psychiatrist and sleep medicine specialist Dr. Michael Mak of the Centre for Addiction and Mental Health in Toronto. Firefighters tell stories of entering burning homes and finding people still sleeping “and not awoken by all the ruckus,” Mak said. On the opposite side of the spectrum are people so hyper-arousable, the bark of a dog three blocks away is enough to keep them staring at the ceiling all night. “Depending on where you are on the spectrum, waking up in the middle of the night can be a problem,” Mak said.

However, normal processes make people prone to 3 a.m. awakenings, Murray said. At that point, melatonin, the hormone that makes people drowsy and encourages sleep, has peaked and is starting to depart the body. Cortisol, the stress hormone that rouses people out of sleep starts to rise, along with core body temperature.

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Most times the waking is light and fleeting. People don’t even remember it. But light awakenings can turn into complete awake self-consciousness if people are under stress.

This hyper-vigilance probably served our early ancestors well. “When people were sleeping in more precarious situations, when we were susceptible to being attacked by predators (humans or otherwise), night was a relative time of stress,” Mak said.

But once we start to ruminate, the body and brain begin to respond as if there is an actual threat, Murray said. As cortisol revs up, “the ‘fight or flight’ response can kick in, which in turn causes more vivid negative thinking,” an unhelpful feedback look that mimics a panic attack.

It’s not clear why we’re prone to picking on ourselves, or why we might tend to be egocentric at night, though Murray has some hypotheses, including that perhaps “all paths of thought just devolve to ‘the self'” when our ability to think through an issue is hampered by all the brain processes trying to put us to sleep.

It’s one thing to shake off a gloomy mindset. The risk of violent deaths also peaks during nocturnal wakefulness, defined as being awake for prolonged periods when the body’s circadian rhythm is in sleep mode.

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After reviewing 15 years of data from suicides and homicides across the United States, examining risks on an hour-by-hour basis, Grandner and colleagues found a five-fold greater risk for suicide, and an eight-fold greater risk for homicide between the hours of 2 and 3 a.m., when adjusting for the number of people who are awake at that time and capable of suicide or homicide. The nighttime risk was highest among teens and young adults, and those under the influence of alcohol or experiencing partner conflict.

“Insomnia, nightmares, substance use, shift work and medical disease may all cause nocturnal wakefulness,” the researchers wrote. But “being awake when reason sleeps likely carries a distinct risk for dysregulated behaviors.” Data is also showing that nocturnal wakefulness can impair our decisions around food, “and why nobody craves a salad at two o’clock in the morning, either,” Grandner told the May webinar. Instead, people have a hankering for highly processed foods high in sugar and saturated fats.

Nobody craves a salad at two o'clock in the morning, either

Michael Grandner, University of Arizona

Waking in the middle of the night isn’t by itself necessarily pathological, Mak said, unless it’s occurring often enough to cause people distress. The ability to stay asleep decreases with age starting around age 60. Medical problems don’t help. “Unfortunately, most men with prostate issues will have to wake up once or twice to use the bathroom,” Mak said. Chronic pain, anxiety, depression — all can interrupt sleep.

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“Any strategy that distracts us from our negative thoughts can help to calm us down,” Murray wrote to National Post. “Reading a book can decrease overnight anxiety.” Slowing the breathing soothes the fight or flight response, he said. “The brain starts to think, ‘There must not be a problem, because I’m breathing like I’m relaxed.'”

Listening to the breathing also helps block unproductive thoughts and slows the breathing “in a way that convinces us we’re safe,” Murray added.

Mak said it’s not helpful to simply tell people not to ruminate if they wake when they should be asleep. “If you tell somebody not to think about anything whatsoever, they’re going to think about everything. That’s how people work.”

Instead, he recommends people leave their beds, move to another (dimly lit) room and distract themselves by doing something boring like a word search puzzle. “It’s simple. The answers are in front of you. You’re just circling hidden words,” Mak said. “The person is putting all their mental faculties into looking at a sheet of paper. They’re not thinking about things that stress them out.

“When they feel that head-nodding feeling that signifies sleep, it’s time to go back to bed.”

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