Introduction
You have probably heard the quote, "Early to bed, early to rise makes a person healthy, wealthy, and wise."
For night owls, staying up late feels normal. Yet, a new large-scale study by Stanford Medicine researchers suggests that working late may be harmful to one's mental health.
The study published in Psychiatry Research examines how our natural sleep preferences, or chronotypes, relate to mental health.[1]
Continue reading to find out more about this intriguing research.
A Quick Re-cap on Chronotypes
Before we get started with the study, let's take a moment to understand what chronotypes are. Simply put, a chronotype is one's innate tendency to feel alert or tired at specific times of the day and night.[2] There are typically three (3) categories:[3]
- Morning Larks (Morning Types): These are people who wake up early. They feel most awake and energized in the morning and usually go to bed earlier.
- Night Owls (Evening Types): These people thrive in the evening. They feel more awake and productive as the day goes on and often stay up late into the night.
- Intermediate Types: These people fall somewhere between morning larks and night owls. They are flexible with schedules and don't strongly prefer mornings or evenings.
Typically, a person's chronotype is determined by a mix of genetics, age, and environment.[4] Teenagers usually like to stay up late. In contrast, older adults tend to wake up earlier.
The Study
In a brilliant research published in the Psychiatry Research Journal, experts from Standford Medicine examined the sleep habits of nearly 75000 adults.[1]
The researchers looked into a concept called "chronotype." This idea relates to whether a person tends to be a morning or evening person.
Past research showed that aligning your sleep routine with your chronotype can be good for your health. However, experts were not entirely sure that this finding was accurate. So, they set out to disprove it by examining a larger population than previous studies.
The participants were all middle-aged or older adults from the United Kingdom (UK). They were asked about their sleep preferences and behaviors. The researchers also gave them active monitors to track their sleep for a week.
Of the 73,880 participants, 19,065 were morning people. There were 6,844 evening people. The rest fell somewhere in the middle. The researchers didn't focus on exact bedtimes.
They divided sleep patterns into three groups: early sleepers (the first 25%), late sleepers (the last 25%), and intermediate sleepers (the middle 50%).
The researchers gathered the data and compared it to participants' health records. They focused on mental and behavioral issues found in the International Classification of Diseases.
A Surprising Result
The researchers found that following a person's chronotype isn't the best choice for mental health. It was better for night owls to sleep against their chronotype.[5]
Jamie Zietzer, a psychiatry professor and the study's lead author, said the findings were clear and surprising. People who go to bed late, whether they are morning or evening types, have more mental health issues. These issues include anxiety and depression.
"The worst-case scenario is undoubtedly the late-night people staying up late," Zeitzer noted.
People who slept at night and kept their natural sleep routine were 20% to 40% more likely to develop mental health problems. This finding was in comparison to those who went to bed earlier.
Night owls who changed to an earlier sleep schedule did better mentally than those who stuck to their usual habits.
Meanwhile, morning people who stayed up late faced some negative effects, but they weren't as bad.
Unsurprisingly, morning larks who kept their early routines had the best mental health outcomes.[1]
How Does Staying Up Late Affect Mental Health?
The researchers looked at the study's findings. Then, they analyzed how staying up late impacts mental health. They examined whether uneven sleep schedules or shorter sleep could explain the results. But it did not.
The researchers also wondered whether poor mental health causes people to stay up late rather than the other way around. They also ruled that out.
Scientists studied participants without mental health diagnoses for eight years. They found that night owls, who sleep late, were more likely to have mental health problems over time.
What, then, is behind this link? Jamie Zeitzer and associates have some ideas. The "mind after midnight" hypothesis is one of the main ones.
Late-night changes in our brain and body can lead to impulsivity, bad moods, poor judgment, and riskier behavior.[5]
"Many harmful behaviors are more common at night," Zeitzer noted. Think suicidal thoughts, substance use, overeating, and even violent crimes. The quiet, isolating hours of late night can be fertile ground for poor decision-making.
Interestingly, even morning people who stay up late appear somewhat protected from these effects. Zeitzer thinks this might be because they know their brains aren't working at full capacity, so they become more cautious.
On the other hand, night owls may feel perfectly fine at 3 a.m., believing they are making great decisions—when they aren't.
Another factor the scientists thought about was how night owls' schedules clash with society's norms.
In cultures like the UK and the US, most people wind down early. So, night owls can feel socially isolated. This isolation may hurt their mental health. Zeitzer thinks that staying up late may not be as harmful in cultures with lively nightlife, like in parts of the Mediterranean.
What Can Night Owls Do?
This news might feel like a blow if you are naturally inclined to stay up late. But there are ways to adjust. Dr. Zeitzer suggests going to bed by 1 a.m.
Try to get some morning sun and keep an early schedule daily, even on weekends. These simple steps can help improve your sleep routine. However, he acknowledges that this does not alter your chronotype.
"Biologically, it's like a rubber band. If you take a day off, you snap back to where your body prefers to be," Zeitzer said.
Concerning the future steps, Dr. Zeitzer and his team intend to investigate further if certain late-night activities, rather than merely the timing, are the true causes of worsening mental health.
"If you enjoy staying up late and doing what others do at 10 p.m. but at 2 or 3 a.m., then maybe that's fine," he surmised.
Final Thoughts
This research shows that our sleep habits impact our mental health, no matter our natural sleep preferences. Prioritizing earlier sleep is a simple but important step for better mental health, whether you're a lark or an owl.
References:
- Lok, R., Weed, L., Winer, J., & Zeitzer, J. M. (2024). Perils of the nighttime: Impact of behavioral timing and preference on mental health in 73,888 community-dwelling adults. Psychiatry Research, 337(115956), 115956. https://doi.org/10.1016/j.psychres.2024.115956
- Montaruli, A., Castelli, L., Mulè, A., Scurati, R., Esposito, F., Galasso, L., & Roveda, E. (2021). Biological Rhythm and Chronotype: New Perspectives in Health. Biomolecules, 11(4), 487. https://doi.org/10.3390/biom11040487
- Vitale, J. A., & Weydahl, A. (2017). Chronotype, Physical Activity, and Sport Performance: A Systematic Review. Sports medicine (Auckland, N.Z.), 47(9), 1859–1868. https://doi.org/10.1007/s40279-017-0741-z
- Kalmbach, D. A., Schneider, L. D., Cheung, J., Bertrand, S. J., Kariharan, T., Pack, A. I., & Gehrman, P. R. (2017). Genetic Basis of Chronotype in Humans: Insights From Three Landmark GWAS. Sleep, 40(2), zsw048. https://doi.org/10.1093/sleep/zsw048
- Night owl behavior could hurt mental health, sleep study finds. (n.d.). News Center. Retrieved February 11, 2025, from https://med.stanford.edu/news/all-news/2024/05/night-owl-behavior-could-hurt-mental-health--sleep-study-finds.html
