Highlights:

  • Chronotype affects depression.
  • Early birds less prone to suffer from depression..
  • Night owls and intermediate chronotypes had no significant differences in relation to depression.

Early birds are those who have the tendency to sleep early and to also wake up early in the morning. Sleeping too much can make you feel tired but also can increase the chances of suffering from diabetes and other heart-related issues. On the other hand, sleeping less has been linked to increased risk for depression and chronic diseases.

Get to know the study and the procedures.

Differently from the above-mentioned study, where we mostly compare the two chronotypes, here we will be mostly focused on the relation between sleeping time and depression. “Prospective study of chronotype and incident depression among middle- and older-aged women in the Nurses’ Health Study II” is a study with leading author Céline Vetter and published during June in the  Journal of Psychiatric Research.

In fact, when trying to determine whether someone is a certain type of chronotype, genes should be taken into consideration. 12 to 42 percent of the chronotype is addressed to genetics. Furthermore, chronotype is also affected by light exposure which is then related to depression risks.

Researchers analyzed data from the Nurses’ Health Study participants, 32470 females with average age 55 years old. Nurses’ Health Study is a questionnaire filled by nurses every two years. In this questionnaire, nurses filled answers about the factors which influence depression like exercising, chronic disease, working schedules, sleep schedules etc. The participants weren’t suffering from depression and the majority of them, 53%, described themselves as intermediate chronotypes, 37% self-reported being early birds and only 10% were night owls. The study lasted from 2009 to 2013.

What did researchers discover?

The study confirmed that chronotype moderately influences and is related to depression along with other factors which are mentioned above. Those participants who had the tendency to sleep and wake up early appeared to have 12 to 27 percent fewer chances of experiencing depression when compared to intermediate chronotypes. Also, early birds appeared to have 18 to 33 percent fewer chances of depression suffering compared to night owls. Night owls didn’t show essential differences to intermediate chronotypes about depression risks.

One can easily understand that chronotype is not a big influencer about depression but when it is put together with other risk factors it has its own importance. Céline Vetter told to the University of Colorado Boulder that:

Do your best to become an earlier bird. Try to get enough sleep and exercise, spend time outdoors, dim the lights at night, and try to get as much light by day as possible.