According to a new study, going to bed after 1 a.m. may negatively impact mental health.
Researchers indicate that an individual’s biological clock—whether they are a morning person or a night owl—has little relevance to these findings.
Sleeping later can lead to less REM sleep, which is crucial for optimal brain function.
If you go to bed later than 1 a.m., you may have a higher risk of mental health issues, regardless of whether you are an early riser or a night owl. This is the conclusion of a new observational study from the Royal College of London in the UK.
The study found that individuals who go to bed before 1 a.m. tend to have better mental health, with fewer reported cases of psychiatric disorders, behavioral and developmental issues, depression, and generalized anxiety disorder (GAD).
Sleep researchers have long pondered the concept of chronotype, which refers to a person’s preference for when during the 24-hour day they like to be awake or asleep.
Sleeping later can lead to less REM sleep.
An individual’s circadian rhythm may influence their personal sleep preferences. Some people prefer to wake up and sleep early, while others enjoy waking up late and going to bed late.
A surprising finding from the study is that at night, when people go to bed after 1 a.m.—even when this aligns with their biological clocks—they exhibit the worst mental health. The group with the least diagnoses of mental health issues consisted of early risers who went to bed before 1 a.m.
The researchers analyzed data from adults living in the community from the UK Biobank database. The study group included 73,888 individuals, of which 56% were female. The average age of participants was 63.5 years, and they averaged 7 hours of sleep per night cycle.
The study was published in the journal Psychiatry Research.
How Sleep Affects Mental Health
Senior study author Jamie Zeitzer, Ph.D., professor of psychiatry and sleep medicine at Stanford University, proposed citing a theory called “The Midnight Mind,” which suggests that the brain operates differently at night, potentially affecting mental health.
Zeitzer explained to Medical News Today: “We believe this relates to individuals feeling isolated when staying up late, as they lack the protective barriers and support that come with social interactions or even knowing that others are awake.”
Sara Wong, Ph.D., a research collaborator at the Franks-Wisden Laboratory at the Royal College of London, noted that this theory is supported by sleep science (Wong did not participate in this new study).
Wong pointed out that staying up late in the modern world often limits total sleep time. She told Medical News Today: “This particularly affects REM sleep, which occurs most significantly in the latter half of the night.”
Wong further explained: “REM sleep is closely related to mood regulation—meaning less REM leads to poorer mood—with changes in REM sleep considered a risk factor for many neuropsychiatric disorders like depression, generalized anxiety disorder, and PTSD.”
The exact role of REM sleep is not yet completely understood, but Wong stated it is related to excitability in the cortex, which can lead to cognitive dysfunction and potentially neurotoxic effects, causing waste accumulation in the brain.
“Perhaps REM sleep is also important in this regard,” Wong said, citing research that shows the clearance of waste debris occurs less during non-REM sleep.
Evening Activity Patterns Linked to Poorer Health
Chronotypes regulate how an individual’s internal clock operates. Although the human internal clock typically spans 24 hours, it also interacts with environmental factors.
With the prevalence of artificial light and other factors like night shift work, “one could argue that our society, in many ways, has not yet adapted well to night owl patterns,” said Jonathan Cedernaes, Ph.D., a researcher in the Department of Medical Sciences, Division of Transplantation and Regenerative Medicine at Uppsala University in Sweden, who did not participate in the study.
Wong noted that evening chronotypes are often associated with poorer health outcomes.
Nevertheless, the study’s findings raise questions about the concept of chronotypes. Zeitzer stated: “This is quite surprising and contrasts with our hypothesis.”
“We entered the study thinking we would find that alignment was the most important aspect of mental health—meaning larks should wake up early and owls should stay up late. We were quite surprised that this was not the case for owls. Not to say being labeled an owl cannot be beneficial for mental health, but overall, staying up late will ultimately have a negative impact on mental health,” Zeitzer remarked.
Optimal Bedtime May Vary
Zeitzer hypothesized about the importance of 1 a.m. as a benchmark for bedtime: “I think it relates to the demographic we studied (middle-aged and older residents of the UK),” he noted, adding that common social patterns may also be a factor.
Cedernaes pointed out the effects of seasonal changes on sleep and timing. He noted: “This also depends on whether areas transition between Standard Time and Daylight Saving Time.”
“Therefore, specific optimal bedtimes may need to account for both season and time zone. For example, some regions, like Spain and Iceland, are not ideally positioned in their time zones, and a lot of sleep-wake behavior occurs much later in such areas,” Cedernaes explained.
However, Zeitzer remains somewhat uncertain. He said: “I don’t think it will change much with dawn timing, but rather with seasonal changes in social patterns.”
