On the broadest level, the study of circadian rhythms, known as chronobiology, is all about the differences between chronotypes: ‘larks’ (so called morning people) and ‘owls’ (or night people). In a recent study, researchers in Berlin discovered that a relationship exists between chronotype and an individual’s preference for dwelling on the past, present, or future.
“Male larks were more future-oriented and less present-oriented,” the authors wrote in their study published last month in Chronobiology International, while “male owls more present-oriented and less future-oriented.” But that was just one of the many things the researchers found found when studying larks and owls.
On the broadest level, each of us may be oriented toward either day or night, but chronobiology also reaches down to our individual cells, which express metabolic function in cyclical patterns as instructed by a genetic clock.
“The entire body is a clock,” Derk-Jan Dijk, director of the Surrey Sleep Research Centre in Guildford, UK, told Nature. “It's a house with clocks in every room and every corner, yet in one way or another they work in an organized way.”
Throughout our body, then, each cell functions at an individual tempo while also working in cadence with the whole. The conductor of this symphony is the suprachiasmatic nucleus (SCN). Not only does this group of neurons tucked within the hypothalamus influence physiological rhythm, the SCN also controls behavior and cycles your brain between wake and sleep. These physiological and behavioral patterns in turn impact the entire physical system of our bodies and are responsible, in part, for establishing good health or causing illness.
It is known, for instance, that mood disorders disrupt circadian rhythms; some scientists suggest that correcting these irregularities may be a new path for treatment. Ongoing research also finds certain disorders, such as obesity and sleep apnea, to be related to chronotype. Because the workaday world is regimented by an external clock, a domino effect is created when chronotype does not sync with the social norm. “Evening types tend to get less and more shallow, non-refreshing sleep during working days,” the researchers of a separate study published earlier this year wrote. Because night owls do not sleep as well as larks, then, they become prone to poor eating habits and this can lead to obesity, which may then cause cardiovascular disease.
Clearly, falling dominoes. But does chronotype influence non-physiological aspects of our selves? Do our circadian rhythms impact our very thoughts?
In the Moment
To investigate rhythm and abstraction, the German researchers searched for a potential link between chronotype and time perspective. “Time perspective (past, present, future) refers to the preference to rely on a particular temporal frame for decision-making processes and behavior,” the authors wrote.
Their study included 706 participants between the ages of 17 and 74. Each participant completed German adaptations of the Morningness-Eveningness Questionnaire (MEQ) as well as the Zimbardo Time Perspective Inventory (ZTPI). What they discovered after analyzing the results was that a relationship existed between chronotype and time perspective: larks were more future oriented, while owls were more present-oriented.
Next, they controlled for age and sex, and found that age and sex had an impact on the chronotype-time perspective relationships. In all age groups, men were uniform in their orientation: larks were more future-oriented, owls more present-oriented. Although the same bias was present among young adult women and girls, women older than 30 had developed a new relationship to time.
“Female adult owls were more present-oriented as well as more past-oriented,” the authors wrote. “Female adult larks were less present-oriented and less past-oriented.”
Sources: Nowack K, van der Meer E. Are larks future-oriented and owls present-oriented? Age- and sex-related shifts in chronotype-time perspective associations. Chronobiology International. 2013.
Lucassen EA, Zhao X, Rother KI, et al. Evening Chronotype Is Associated with Changes in Eating Behavior, More Sleep Apnea, and Increased Stress Hormones in Short Sleeping Obese Individuals. PLOS ONE. 2013.