A large-scale new study from Stanford Medicine suggests that no matter your chronotype, late bedtimes significantly increase the risks of depression, anxiety, and other behavioral disorders.
The results were very unexpected, Jamie Zeitzer, senior author of the study and professor of psychiatry and behavioral sciences at Stanford, told The Epoch Times.
The Brain After Midnight
While the reasons early risers tend to have better mental health than night owls remain unclear, we know it is related to the timing of sleep, Renske Lok, a postdoctoral scholar in psychiatry and behavioral health and the lead author of the Stanford Medicine study, told The Epoch Times.
One factor is that nocturnal activity often breeds impulsive and maladaptive behavior, she said. The brain operates differently during nighttime wakefulness, especially in areas like risk assessment, behavioral inhibition, and cognitive control, she added.
The researchers initially expected that aligning your sleep schedule with your biological chronotype or sleep preference would benefit mental health the most. But their analysis of data from 73,888 adults, which was published in Psychiatry Research, showed that, regardless of whether a person naturally prefers mornings or evenings, going to bed earlier is associated with better mental health outcomes. An early bedtime seems to override the impact of chronotype when it comes to mental well-being.
When people align with societal norms and more people are awake simultaneously, it can promote better mental well-being, Ms. Lok noted. Night owls, however, may experience poorer mental health due to misalignment with common sleep patterns, she added. They’re often expected to wake up early for work despite insufficient sleep, leading to grogginess, reduced performance, and adverse mental health outcomes.
A 2022 review in Frontiers in Network Physiology explores the “Mind after Midnight” hypothesis, suggesting significant late-night wakefulness leads to behavioral and cognitive dysregulation, resulting in people seeing the world negatively and engaging in risky behaviors. It discusses how day-night cycle disruptions can result in maladaptive behaviors like substance abuse, violent crime, and suicide.
The review also examines differences in executive functioning, reward processing, and mood during nocturnal wakefulness, proposing that prefrontal disinhibition, altered reward processing, and attentional biases contribute to psychiatric disorders and behavioral issues.
Sleep Cycles
In his book “Why We Sleep,” Matthew Walker, who holds a doctorate in neurophysiology and is a professor of neuroscience and psychology at the University of California–Berkeley, explains night owls’ brain state, particularly the prefrontal cortex, which remains in a sleep-like state in the early morning. This area governs logical reasoning, higher-order thinking, and emotional regulation.
Mr. Walker likens a night owl’s brain forced to wake early to a cold engine starting: It takes a long time to warm up and function efficiently.
Sleep disruption is a well-known feature across all anxiety disorders. Research suggests that non-rapid eye movement (NREM) slow-wave deep sleep has an anti-anxiety effect on brain networks, indicating that NREM sleep could serve as a therapeutic target for meaningfully reducing anxiety levels, according to a 2020 article in Nature Human Behavior.
During a typical 90-minute sleep cycle, the ratio of NREM to REM sleep changes dramatically throughout the night. The first half is dominated by deep NREM sleep, with very little REM sleep, while the balance shifts in the second half, with minimal deep NREM sleep and an abundance of REM sleep, Mr. Walker noted.
According to Mr. Walker, missing out on NREM sleep in the first half of the night impairs the process of removing and pruning unnecessary neural connections.
However, Mr. Zeitzer said that, according to his team’s research, the ratio of NREM to REM sleep, as well as the depth of REM sleep, should not be impacted if night owls go to sleep late.
The study’s findings suggest that regardless of whether night owls sleep in or not, their mental health is still affected, independent of the total sleep duration—even if, for example, night owls go to bed by 2 a.m. and sleep for an extended period.
Avoiding Late-Night Pitfalls
For improved mental health, the Stanford study recommends hitting the hay before 1 a.m. However, achieving an early bedtime can be easier said than done.
Vigorous exercise late at night activates the sympathetic nervous system, releasing stimulating hormones and neurotransmitters that make it harder for our minds and bodies to transition into deep sleep, Dr. Rose Anne Kenny, a geriatrician, professor of medical gerontology, and author of “Age Proof,” wrote in her book.
Late-night eating can also be a contributing factor, especially when it involves foods and drinks high in tyramine, an amino acid that triggers brain alertness. Aged cheeses, wines, certain beers, and cured meats are among the culprits.
Dr. Kenny noted that tyramine stimulates the production of norepinephrine (noradrenaline), a neurotransmitter involved in the sympathetic nervous system’s fight-or-flight response. This can make us feel alert and awake, preventing an early bedtime.
Tips for Night Owls
For night owls looking to adjust their sleep schedules, Dr. Kenny suggests a gradual approach: changing food and sleep intake by 15 minutes earlier per day until the desired sleep times are achieved.
She further recommends incorporating sleep-promoting foods that enhance neuropeptides, like tryptophan and melatonin. These include turkey, almonds, chamomile tea, fatty fish, kiwis, milk, cottage cheese, tart cherry juice, and bananas.
Deep sleep can also be enhanced through sound stimulation, such as listening to pink or white noise, Dr. Kenny added.
