Night owls, early risers, personality and insomnia

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In the past decades, there has been a growing body of research regarding night owls and early risers. Night owls do not only need more coffee to get through the working day, but they also have serious health risks.

“A growing body of research suggests that being a night owl could have negative effects on health, including the possibility of increasing a person's risk of early death. Many of these effects may be attributed to a misalignment between a person's internal clock, or circadian rhythm, and the socially imposed timing of work and other activities.” from this source

What makes someone a night owl? Being a night owl is partially heritable and genetic researchers have found out that being a night owl correlates with mental problems such as depression and schizophrenia. There were, however, no real night owls in our evolutionary past, we aren’t a nocturnal species after all. So it does seem likely that night owls do suffer from a misalignment of their circadian rhythm, instead of being programmed to be night owls by evolution. So, what keeps us awake at night?

Surprising personality might give us the key to the answer here.

Night owls often have the following traits:

• able to be highly focused/hyperfocused (pulling an all-nighter just to finish the code)
• are more intelligent (but tend to earn less)
• are less conformist
• tend to procrastinate
• tend to struggle with routine 9-5 jobs
• have a more addictive personality (alcohol, cigarettes, video-gaming)
• seek out novelty (openness to experience)

Larks, on the other hand, tend to be

• conscientious
• driven and hard-working
• more cooperative
• tend to procrastinate less

I have argued before that our personality types are determined by our evolutionary ancestral mode of subsistence, farming vs hunting-gathering. The chronotype “lark” goes hand in hand with the personality type “farmer”. Early farmers had harder lives than hunter-gatherers, they had to get up early to get their work done, and typically only had little time to rest in between and they had to be very cooperative to work their fields and animals. They had to be able to conscientiously focus on rote work for long periods of time.

Hunter-gatherers on the other hand frequently often woke up at night. They had to be more alert to potential dangers. Studies among the Hadza (African hunter-gatherers) have shown that they often wake up at night and rarely anybody sleeps from dusk to dawn. It can be assumed that hunter-gatherers are more sensitive to physical stimuli (such as noise) that wake the up when potential danger threatens. Hunter-gatherers work in bursts rather than routinely, i.e. they hyperfocus when required and rest for much of the time in between.

So, how do hunter-gatherer types become night owls? My guess is, they are simply better able to focus in the late (or very early) hours when nobody is around. They have higher sensibilities and are therefore more easily destructible during the daytime, in particular at work when the workplace is buzzing with people. 

In our modern world stress might keep hunter-gatherer types awake more easily than farmer types as stress makes them hyperfocus, fall asleep harder due to not being able to switch off and wake up more often during the night. In fact, this is exactly the pattern that can be observed in night owls: being a night owl and the risk of insomnia go hand in hand. Scientists know that night owls have worse sleep than larks. This can't be an adaptation per sé, being a night owl is something like a forced and/or necessary evil.