What Happens to Sleep When You Remove the 9-to-5
Different countries have measurably different sleep schedules — shaped by longitude, light, labor policy, and cultural norms. Till Roenneberg's MCTQ data across 50+ countries shows the patterns.
In this article8 sections
Yes, different countries have measurably different sleep schedules. Till Roenneberg’s Munich Chronotype Questionnaire (MCTQ), collected from more than 200,000 participants across 50+ countries, shows systematic variation in chronotype and sleep timing tied to longitude, latitude, labor culture, and social institutions — not individual preference.
When the 9-to-5 is removed, modified, or never existed, the underlying variation becomes visible. Some of it is biological. Most of it is structural.
Germany, 1990: The Longitude Finding
When East and West Germany reunified in October 1990, they shared the same time zone overnight — but their inhabitants didn’t share the same biological clocks.
Roenneberg’s MCTQ data shows that former East Germany, which had been administratively aligned with Moscow time for decades, carried chronotypes running approximately 30 minutes later than former West Germans living at similar latitudes. This wasn’t a product of politics. It was a product of longitude.
The finding that came out of this natural experiment: every degree of longitude east of a time zone’s western boundary correlates with roughly 4 to 6 minutes of later chronotype. Berlin sits 13 degrees east of the meridian at the western edge of Central European Time. The body reads local solar time, not the clock on the wall. When administrative convenience puts a city far east of where its time zone “should” be, its residents’ biological clocks drift later relative to the social schedule — producing chronic misalignment that looks, at the population level, like a 30-minute version of social jet lag baked permanently into the calendar.
This is the most underappreciated finding in chronobiology: social jet lag is not just a behavioral phenomenon. For a significant share of Europe’s population, it is a cartographic one.
Japan: The Permission to Collapse
Japan is simultaneously one of the most sleep-deprived nations measured by the OECD and one of the most culturally tolerant of visible sleep. The 2021 OECD data puts Japan’s average nightly sleep at 6 hours 35 minutes — the lowest among surveyed nations, compared to a global average of 8 hours 22 minutes.
The cultural term is inemuri: roughly translated as “sleeping while present.” A salaryman asleep on a Tokyo commuter train, or a manager with his head down in a meeting, is not being rude. He is signaling that he worked hard enough to exhaust himself. The sleep is evidence of dedication; the public setting confirms he hasn’t retreated from his duties to recover privately.
The paradox worth sitting with: inemuri doesn’t increase total sleep time. It legitimizes its visible deprivation. Japan has built a cultural accommodation for a system that causes the condition it accommodates. The permission to sleep in public functions less as a recovery tool and more as a release valve that makes unsustainable working hours feel sustainable. A closer look at inemuri on its own goes further into a single country’s version of this than a six-country survey like this one has room for.
The Hadza of Northern Tanzania: A Different Starting Point
Jerome Siegel and colleagues at UCLA published a study in Current Biology in 2015 tracking the sleep patterns of the Hadza, a hunter-gatherer group in northern Tanzania living without artificial light or modern schedules. The findings disrupted several assumptions about what “natural” human sleep looks like.
The Hadza slept 6.2 to 7 hours per night — less than most sleep recommendations for industrialized populations, and roughly consistent with Japanese averages. They went to sleep approximately 3.3 hours after sunset and woke near sunrise. They experienced almost no insomnia. They had no term equivalent to “sleep hygiene” in their vocabulary.
What Siegel’s team observed is that their sleep tracked temperature more closely than light — dropping off as nighttime temperatures fell and rising as temperatures climbed in the early morning. The implication is that some features of sleep disorders as they appear in industrialized societies may be partly an artifact of two specific conditions: exposure to artificial light after sunset, and sleeping in thermally stable environments that remove the temperature gradient the circadian clock may use as a secondary anchor.
This doesn’t mean reverting to open-air sleeping solves insomnia. It means the default human sleep profile looks different from what industrialized assumptions suggest, and the comparison illuminates what modern environments are doing to the system.
Spain: A Chronotype System That Broke Its Own Logic
Spain runs one of the latest dinner cultures in Europe. Evening meals at 9pm or 10pm are standard across much of the country, particularly in cities. Bedtimes follow: the Spanish average bedtime, surveyed across multiple studies, runs approximately 45 minutes to an hour later than the European mean.
This system originally had a structural counterpart: the siesta. A midday rest of 20 to 40 minutes partially compensated for the later sleep onset, splitting the day into two productive windows and reducing the pressure on nighttime sleep to carry all of the day’s cognitive weight.
The siesta is dying. A Sociedad Española de Sueño survey found daily siesta use dropped from approximately 16% of Spanish adults in 2012 to roughly 9% in 2022. The cause is mostly economic: office-based work and open-plan environments make midday sleep impractical in ways that agricultural or family-business schedules did not.
What remains is the late dinner, the late bedtime, and an earlier morning start required by the European business calendar. Spain is, by this reading, a country that phased out half of its circadian adaptation without modifying the other half. The result is a population carrying structural sleep debt that grows as siesta use declines.
Arctic Norway: What Happens When Light Disappears
At 78 degrees north latitude, Svalbard — the Norwegian archipelago that hosts the world’s northernmost permanent settlement — sees no sunrise for roughly four months in winter and no sunset for four months in summer. If circadian rhythms were driven entirely by light, the population here should show extreme seasonal disruption.
Studies from Svalbard and similar high-latitude environments show something more nuanced. Human circadian rhythms do freewheel during polar night — individuals show somewhat more variable sleep timing without consistent light cues — but they destabilize less dramatically than the light deprivation would predict. During midnight sun, when light is constant, rhythms remain more stable than during polar night despite the absence of darkness.
The interpretation: social zeitgebers — meal times, work schedules, alarm times, the social rhythm of a community — function as circadian anchors that partially substitute for photic cues. The Svalbard findings don’t mean light doesn’t matter. They suggest the circadian clock uses whatever the most consistent available signal is, and in high-latitude human communities, that signal is often social rather than solar.
South Korea: When the Schedule Is the Product
South Korea is the most sleep-deprived developed country in the OECD dataset. A 2016 study from Kyung Hee University found Korean high school students averaged 5.5 hours of sleep on school nights — well short of what any major sleep medicine body considers adequate for healthy adolescent development.
The structural cause is well-documented: hagwon culture. Hagwons are private tutoring academies that run evenings and weekends, filling the hours after formal school ends. For a competitive high school student, the day may begin at 7am and not end until the hagwon closes at 10pm or later. The competitive university entrance examination — the suneung — concentrates enormous economic stakes into a single test, making opting out of this schedule feel impossible for families who can afford not to.
This is sleep deprivation as a feature of a credentialing system, not a bug of individual behavior. The research on consistent wake times documents what this kind of chronic truncation costs in cognitive terms. In South Korea, it’s not primarily about alarm habits — it’s about whether the system the alarm serves has built in room for the sleep it interrupts.
On wake-time accountability: The countries with the healthiest sleep patterns share structured external time cues — social meals, predictable work rhythms, or strong light cycles. DontSnooze is one way to add an external time cue when the natural ones have eroded.
The Thread
Six countries. Six different structural conditions. The variation in sleep patterns across them is not primarily a story about individual discipline or cultural character. It is a story about what happens when institutions, longitude, light, and economic incentives intersect with biology.
Germany’s map problem, Japan’s labor norms, the Hadza’s temperature cues, Spain’s disappearing siesta, Svalbard’s social anchors, South Korea’s examination system — each reveals a different lever. The lesson that cuts across all six is that no population sleeps according to pure preference. Sleep schedules are shaped by what time the trains run, what time dinner is served, what latitude you were born at, and what examination your children must pass. Willpower barely registers as a variable. The same logic scales down to individuals: a streamer running a genuinely late schedule built around when an audience is actually online and watching them wake up isn’t undisciplined — they’re operating on a chronotype and a work structure just as legitimate as any of the six systems above, at the scale of one person instead of a nation.
Frequently Asked Questions
Do different countries really have different average sleep times?
Yes, measurably. OECD data from 2021 shows average nightly sleep ranging from 6 hours 35 minutes in Japan to over 8 hours in populations with less rigid work schedules. Till Roenneberg’s MCTQ database, covering 200,000+ participants across 50+ countries, shows that chronotype — the biological preference for sleep timing — varies systematically with longitude, latitude, and age, independent of individual preference.
Why does longitude affect when people sleep?
The human circadian clock tracks local solar time rather than the time zone on the clock. In regions where political or administrative convenience places cities far east of where their time zone’s solar noon falls, residents experience a chronic mismatch between clock time and biological time. Roenneberg’s data suggests roughly 4 to 6 minutes of later chronotype per degree of longitude east within a time zone — a small number per degree that adds up across the span of large time zones.
What is inemuri and does it help with sleep deprivation?
Inemuri is a Japanese cultural practice of sleeping in public or semi-public settings — trains, meetings, parks — that is interpreted as evidence of hard work rather than laziness. It does not meaningfully compensate for Japan’s average 6 hours 35 minutes of nightly sleep. It functions as a cultural accommodation that makes severe sleep restriction socially sustainable rather than one that reduces it.
What did the Hadza sleep study find?
Jerome Siegel’s team at UCLA (Current Biology, 2015) found that the Hadza, a Tanzanian hunter-gatherer group, slept 6.2 to 7 hours per night with minimal insomnia, tracked temperature more closely than light as a sleep cue, and had no cultural concept equivalent to “sleep hygiene.” The finding is significant because it challenges the assumption that more sleep or stricter sleep hygiene is what eliminates insomnia — the Hadza achieve low insomnia rates through environmental regularity, not behavioral intervention.
Is the Spanish siesta dying out?
Yes. Sociedad Española de Sueño data shows daily siesta use fell from approximately 16% of Spanish adults in 2012 to roughly 9% in 2022. The decline tracks Spain’s shift toward open-plan office culture and European business hours. Late dinners and bedtimes remain, meaning the population is losing the compensatory rest practice without changing the schedule that required it.