To sleep in or not? The science of chronobiology and the challenges to being a night owl

The science of chronobiology investigates biological rhythms and has shown that people can be classified as early, late or intermediate chronotypes. In layman terms, that translates to whether you are a ‘lark’, a ‘night owl’ or fall somewhere in between.


Sleepy young woman in bed

The NorthFace100 Singapore trail race is scheduled for an early morning start this year. As I prepare to be flagged off tomorrow at 5 am, I have to admit that it is with mixed feelings. An early start means you can cover more miles before the sun peaks and beat the heat. But to be completely honest, I am not sure I am an early bird.

The science of chronobiology investigates biological rhythms and has shown that people can be classified as early, late or intermediate chronotypes. In layman terms, that translates to whether you are a ‘lark’, a ‘night owl’ or fall somewhere in between.

We have internal ‘circadian’ clocks, programmed by genetics, which determine activity and sleep. Research into DNA has shown that the length of the gene that determines the circadian clock is different in persons with different chronotypes with early risers having the gene with the longer length. But what makes you wake early or late depends on several factors that include genetics, the solar clock and your social environment.

Light and darkness cues interact with our body to make us active or sleep. Since the circadian clock runs for a bit longer than 24 hours, it needs to compress and synchronize with the solar clock. Our body does this by exposing more of its internal day to light and more of its internal night to darkness. Therefore, persons with slower internal clocks tend to be later chronotypes – experiencing a sort of permanent jetlag.

Add to this social jetlag. A third factor that determines when you sleep, how long you sleep for and when you hit the midsleep period is the social clock. Human society is engineered around waking up early and getting productive quickly. While this is great in rural societies, it is simply not applicable to the industrialized, modern world that is always awake. Markets open when others close and someone somewhere is online and ready to connect at all times. Streets are lit 24 hours and most nightclubs are open till morning with lights, music and conversation streaming non-stop. This is the world today, one that the night owl thrives on. Or, at least does so until he/she has to start work in the morning without enough sleep in between.

Late chronotypes are therefore significantly sleep deprived during the workweek where external activity demands are not synchronized with their internal clocks. They are always trying to catch up on their sleep debt during the weekends or what researchers term ‘free days’. This sleep deprivation impacts mostly adolescents struggling through the school day and adults at work. This is because chronotype also changes during lifestages with children and elderly persons being natural early risers while late waking which is the norm in adolescence, continues well into mid-life.

There are significant consequences to being out of sync with a world that demands vigilance, attention, focus, memory, and productivity at a time when you are not fully awake yet. Research has shown increased accident rates, decreased attention, low mood and learning deficits are associated with less and/or disturbed sleep. In fact, late chronotypes seem to be more vulnerable to depression and higher consumption of nicotine and alcohol.

Yet, there is considerable value and goodness associated with being an early riser while sleeping in is looked down upon, despite research showing that late risers are not ‘bad’ or ‘lazy’. We are not ready yet to shake off the moral stigma attached to late rising and change work and school start times to accommodate different chronotypes. Meanwhile, it seems like a good practice to expose yourself to more light during activity periods earlier in the day to stimulate your internal clock and advance your sleep. Training to sleep and wake up earlier and spending waking hours outdoors in broad daylight or using brighter light indoors, just might offset the sleep debt on workdays. You canot change your chronotype, but you can train yourself to adapt to the external environment.

Interestingly, researcher Ronenberg’s Munich Chronotype Questionnaire classifies me as a slight early riser with my sleep patterns being roughly the same on weekdays and free days. Still, to be on the safe side, I will hit the sack earlier tonight in preparation for the early morning race and hope that my body is sufficiently warmed up by the time I get to the start line.

Read Till Ronenberg’s book “Internal Time: Chronotypes, Social Jetlag and Why You’re So Tired’ for an interesting journey through research on sleep patterns. Visit Ronenberg’s website of the Munich Chronotype Questionnaire for an assessment of your chronotype provided to your email address with recommendations

By Shrimathi Swaminathan on 4 October 2013 at 10:36
Posted in Lifestyle and Behaviour