From an early age, we’re taught that getting up early is good for us. Sayings like The early bird catches the worm and Early to bed and early to rise makes and man healthy, wealthy and wise are part of the culture and have a certain moralizing force. People who go to bed early and get up early are upstanding and productive. People who go to bed later and wake up later are degenerate and lazy.

Nowadays, however, there’s a growing body of thought to say this is not only wrong, but also counterproductive. Research into our internal body clocks–what’s called chronobiology–shows that people have naturally different sleep patterns and therefore work best at different times of the day. So, while some of us are indeed most productive in the morning, many of us only snap into our highest gear later in the day.

Chronobiologists have identified two polar-opposite sorts of people: type As who wake up early in morning, even on weekends; and type Bs, who accumulate “social jet lag” during the week–the difference between their personal clock and the socially-directed one–that they need to work off by sleeping longer at weekends. (The term “social jet lag” was popularized by the German chronobiologist Till Roenneberg in his book Internal Time. See a good review here; a charming video made by Roenneberg’s daughter is below).

The implications of internal clock research are profound. For starters, research suggests the standard 9 to 5 working day is antiquated, reflecting an agrarian economy (where everyone needs to be up with the lark) not a globalized knowledge one. Second, it implies that making everyone start the day at the same time is fundamentally unfair to people who aren’t at their best in the morning. And three–more positively–it says we might engineer a rise in productivity if we organized things differently.

The start-early norm may be most damaging to kids because the incidence of B-types is highest in younger years (see chart). A recent study by the University of Kentucky, comparing the performance of elementary students with different school start times, found that early starters clearly did worse than later starters. Similarly, studies by Christoph Randler at the University of Heidelberg report that students tend to do better in exams later in the day.

Schools in Denmark, which have experimented with different start times, have also seen positive results. For example, the Vorbasse School introduced flexible hours for 7th, 8th, and 9th graders. For certain classes, students could choose between an 8-10 a.m. time slot and a 2-4 p.m. one, according to their chronotype. After a year, grades rose from an average of 6.1 to 6.7 (on a 12 point scale). Similarly, the Ungdomshoejskole secondary school moved from a start-time of 8:30 a.m. to 10 a.m. Teachers had to develop extra lesson materials because the students were so much more alert and willing to learn.





Camilla Kring, a Danish work-life consultant, argues that the benefits don’t only extend to students. Kring, who has a PhD in work-life issues, interviewed parents of kids at Frederiksberg Ny Skole (New School), which offers a choice between 8 a.m. and 1 p.m. or 9 a.m. and 2 p.m. (The first group gets its most intensive teaching between 8 a.m. and 9 a.m., the second group between 1 p.m. and 2 p.m.) Many said their kids were easier to handle.