Which came first, the sleepiness or the culture? Is there more narcolepsy in Japan?

I’ve been reacquainting myself with sleep-related issues of late, as half of my current placement is in a sleep disorders team. When looking into narcolepsy, I was intrigued to note that rates of narcolepsy are about four times higher in Japan according to self report than they tend to be elsewhere. This got me thinking about my sleep-related observations from the two years I spent there, and I wondered about differences in the way that sleep seems to be conceptualised in Japanese culture.

When I lived in Japan, I saw a lot of people asleep during the daytime. Coming from the UK, I was initially taken aback by this, especially when it occurred at work in educational settings. In Japanese culture, presence is more important that attention: it is okay to be asleep as long as one is present at an event, which conveys the sleeping-yet-present person’s respect for the occasion. It is also (perhaps paradoxically to a Westerner) perceived as evidence of how hard they work. Learning this allayed my dismay somewhat when I taught a demonstration lesson at a local high school with the head of English from my base school, and some of the teachers in the audience went to sleep!

Another frequent sighting was of people sleeping in cars outside offices. I asked about this, and apparently it related to the Japanese approach to punctuality: to be early is to be on time, to be on time is to be late, and to be late does not happen. Thus, these sleepers had arrived so early for their meetings that they had time to sleep. Being spotted sleeping might also communicate their respect for the person they were meeting with.

My students were often visibly tired and with good reason: after school, they were made to attend juku, or cram-school until around midnight every weeknight. Apparently, they learned “how to be Japanese” at daytime school, then learned how to pass their exams in the evenings. This meant that the post-lunch classes could feel like the graveyard shift, as starch and sleepiness conspired to send the students into a soporific stupor.

More recently, Japanese companies have encouraged their staff to take siestas in a bid to boost productivity. According to the linked article, Japanese workers tend to get less sleep than those in any other country. Napping seems to have been part of the Japanese approach for some time: anecdotally, I heard that there was an old saying that “when a Samurai is not fighting, he sleeps”. There seems to be an implicit balance between fierce activity, and sleep, which seems to be reflected in modern-day Japanese life. The tendency towards napping means that people opportunistically sleep in various locations, and might also have contributed to the pragmatic genius of the capsule hotel (see photo atop this post for visual elaboration).

Interpreting the Japanese data in relation to increased incidence of narcolepsy in a clear-cut way is difficult. Firstly, this was based on self-report surveys of thousands of people of working age who were in work, and school-age people who were at school, in a country whose culture encourages people to be seen to be working hard, and where being sleepy at work or school is framed positively. This means that respondents might have been more likely to report feeling sleepy during the daytime than respondents from other countries, where feeling sleepy and sleeping at work might be looked on less favourably. The reliance on self-reports from participants, and the fact that no polysomnography was conducted to objectively verify and quantify the extent of their narcolepsy serves to make the data somewhat less compelling. This would be required in the UK. Still, the figures suggest that there are differences in narcolepsy rates and I wondered about other possible hypotheses.

Perhaps having a culture in which sleep is positively framed results in people sleeping more during the day, which in turn gives rise to difficulties sleeping at night as people have less need to sleep. Other cultures which have siestas do not report such high levels of narcolepsy, but perhaps they tend to have more time set aside and the sleep is not so opportunistic, so the quality of sleep might be better, leading to less unwanted sleepiness.

Perhaps people in Japan are generally more prone to intrusive daytime sleepiness than people in other countries, and their relatively homogeneous society has meant that this trait has been preserved. Perhaps this gave rise to their cultural permissiveness of sleep and sleepiness, and the increased incidence of self-reported traits of narcolepsy. Maybe there is an interaction of these factors. Perhaps there are other factors at play. Maybe I’m just a little sore about people falling asleep in my class, and this post is a desperate defence against the possibility that my teaching was sleep-inducingly boring!

Photo – Capsule Hotel by Charlie Tyack