It rarely feels like a decision. One more episode, one more scroll, one more reply to the group chat, and suddenly the clock on your phone reads 1:17 a.m. For many of us, the late night has become part of who we are: the quiet hours when the house finally settles, the traffic noise fades, and the day at last belongs to us. Plenty of us have long made peace with it by declaring ourselves night owls.
A large study from Stanford Medicine suggests that label may not protect us as much as we would like. Its central finding is simple and a little unsettling: going to sleep late is linked to poorer mental health, whether or not you are wired to be an evening person.
What the Stanford study on sleep and mental health found
Published in the journal Psychiatry Research in May 2024, the study followed nearly 74,000 middle-aged and older adults in the United Kingdom. Led by postdoctoral scholar Renske Lok, PhD, with Jamie Zeitzer, PhD, professor of psychiatry and behavioral sciences, as senior author, the research team compared two things that are easy to confuse: a person’s chronotype, or their natural preference for mornings or evenings, and the hours they actually kept.
Participants described their own sleep preferences, then wore a wrist-based activity monitor for seven days to record when they really slept. Their mental health was drawn from medical records, covering any diagnosed mental or behavioral disorder. Rather than drawing a line at a fixed bedtime, the researchers sorted everyone by comparison with the group: the earliest quarter of sleepers, the latest quarter, and the half in between.
The results ran against the team’s own expectations. Earlier research had suggested that living in sync with your chronotype was protective, so the scientists assumed night owls would do best by honoring their late rhythm. Instead, both morning and evening types who went to bed late showed higher rates of conditions such as depression and anxiety. Zeitzer has said his team spent six months trying to disprove the finding before accepting it.
Why being a night owl is not a free pass
The group that fared worst was the one many of us would have expected to be fine: self-described night owls who stayed up late, exactly as their bodies preferred. Compared with night owls who kept earlier or intermediate schedules, they were between 20 and 40 percent more likely to have received a mental health diagnosis. Evening types who went to bed earlier did noticeably better, while morning people who rose early had the healthiest profiles of all.
Crucially, the difference could not be explained by how long people slept or how regular their schedules were. The researchers also checked whether poor mental health was simply keeping people awake, rather than the other way around. In a subset of participants with no prior diagnosis, tracked over the following eight years, the late-sleeping night owls were still the most likely to develop a mental health condition.
From this, the team arrived at a practical recommendation: aim to be asleep before 1 a.m. Zeitzer has been careful to frame that figure as a guide drawn from this particular population of older British adults, not a universal deadline. Among college students, he noted, 1 a.m. would hardly count as late. The more useful takeaway is the direction of travel: chronically pushing sleep deep into the small hours appears to carry a cost of its own.
The “mind after midnight”: what may be happening in the small hours
The study shows a link, not a cause, and Zeitzer has openly acknowledged that the reason behind it remains the big unanswered question. His leading theory points less to sleep itself and more to what we do while awake at that hour.
A body of research known as the “mind after midnight” hypothesis proposes that the brain behaves differently late at night, tilting us toward impulsive choices, darker moods, and weaker judgment. Several harmful behaviors, from heavy drinking to overeating, also tend to be more common at night. Zeitzer has suggested that morning people may sense their brains are not at their best after midnight and hold off on big decisions, while night owls feel sharp and confident, and act on it.
Another possible factor is isolation. In much of the United States and the United Kingdom, few people are awake and around late at night. Zeitzer has speculated that in cultures where evenings are more communal, staying up might look quite different. It is an intriguing thought for a country like ours, where late dinners, family gatherings, and long conversations over kape are part of the social fabric, though it remains a hypothesis rather than a finding.
Why this matters for Filipinos
The research was conducted in the U.K., but its questions land close to home. A 2023 regional survey by consumer research firm Milieu Insight found that 56 percent of Filipinos sleep less than the recommended seven hours a night, the highest share among the Southeast Asian countries surveyed.
The reasons are woven into contemporary Filipino life. As Dr. Jimmy Chang of the Philippine Society of Sleep Medicine has explained to GMA News, night shifts in the business process outsourcing sector, long commutes, and heavy internet use all push bedtimes later and chip away at rest. For many, the hour after midnight is the only stretch of the day that feels like their own.
One important caveat: the Stanford study did not look specifically at night-shift workers, whose schedules are shaped by necessity rather than habit. If your work keeps you up through the night, a conversation with a physician or sleep specialist is the best place to start.
How to move your bedtime earlier, gently
You do not need to reinvent yourself as a 5 a.m. riser. Zeitzer himself concedes that shifting a night owl’s schedule is easier said than done, and that your underlying chronotype will not change. What can change is the routine around it. A few unglamorous habits do most of the work:
- Seek morning light. Time in daylight soon after waking, even a short walk to the corner store or coffee on the balcony, helps nudge your body clock earlier.
- Keep the schedule on weekends. Zeitzer compares the body clock to a rubber band: take a day off from your routine and it snaps back to where it wants to be.
- Let the bed be for sleep. Sleep physicians commonly advise keeping phones and television out of bed and setting screens aside well before lights out.
- Watch the afternoon coffee. Caffeine late in the day can quietly delay the moment you are able to wind down.
- Make the room restful. A cool, dark, quiet bedroom, no small feat in a Metro Manila summer, signals to the brain that the day is done.
- Move in small steps. Shifting bedtime by 15 to 30 minutes at a time, and holding it, is more sustainable than an overnight overhaul.
Timing is only one part of the picture. The American Academy of Sleep Medicine describes healthy sleep as a combination of sufficient duration, good quality, appropriate timing, and regularity, with at least seven hours a night for most adults.
Looking for more on staying well? Read our report on rising influenza-like illnesses amid the rainy weather, and see what one study found about chronic pain and the risk of high blood pressure.
The bottom line
The Stanford findings do not make night owls wrong, and a single late night is no cause for alarm. What they suggest is that the habit of regularly living past 1 a.m. deserves a second look, and that calling yourself a night person may not offer the cover we once assumed. The researchers’ next step is to study which late-night activities matter most. Until then, the most generous thing you can do for your mind may be the simplest: put the phone down a little earlier, and let tomorrow begin with a rested version of you.
If you or someone you know is struggling with their mental health, the National Center for Mental Health Crisis Hotline is available 24/7 at 1553 (toll-free landline), 0917-899-8727 or 0966-351-4518 (Globe/TM), and 0908-639-2672 (Smart/Sun/TNT).
Sources
- Stanford Report, “Sleep study finds night owl behavior could harm mental health” (May 2024)
- Lok, R., et al., Psychiatry Research (2024)
- Grazia USA, “Staying Up Past Midnight Is Quietly Wrecking Your Mental Health” (October 2026)
- Milieu Insight, “Filipinos most sleepless people in Asia, 4th in the world” (2024)
- GMA News, “Why are many Filipinos not getting enough sleep?”
