Bakit tayo natutulog at nagigising araw-araw?

This is my original reply to Pinay Observer for her Pinoy Scientists website. As you can see, the second photo is different as well as the answer to the fourth question. The photo was changed because she could not find me in this photo, and I won't tell where I am in the photo. Haha. The answer to the fourth question was too long for the website.

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1) What do you do?
I am doing a PhD in Chronobiology. We try to explain several properties of biological clocks using mathematical models. We focus on circadian oscillations which have periods close to 24 hours.

2) Where do you work?
I work in the University of Groningen, Netherlands.

3) Tell us about the photos?
(a) Discussing chronobiology problems with a group of PhD students at the 2009 European Summer School in Chronobiology which was held in Krakow, Poland.


(b) Expressing solidarity with the cleaners in the Netherlands at a nationally-coordinated March for Respect organized by the FNV (Federation of Dutch Trade Union).


4) Anything else you want to share?
We all sleep and wake up everyday. Our sleep-wake schedule is governed by the circadian clock system in our body. It is mainly orchestrated by a master circadian clock which is the suprachiasmatic nucleus (SCN), a group of around 10,000 neurons in the hypothalamus and directly sits at the gate where the optic nerve enters the brain. The location of the SCN may have a functional role as its important function is to synchronize the entire body to the environmental light-dark cycle.

If we live in a cave for several days without any information of the 24-hour light-dark cycle, we will eventually sleep and wake up with a period different from 24 hours. This period is our so-called freerunning period and there is diversity in its value from individual to individual: some have short (meaning less than 24 hours) and others have long periods. It was found from several experiments that humans have an average period of around 24 hours and 15 minutes. There is a relationship between a person's freerunning period and his/her so-called chronotype. A person of early chronotype is sometimes called a morning person while those of late chronotype evening persons. Although there are other factors involved, a morning person usually have a short freerunning period and an evening person a long freerunning period. Circadian biologists are looking into this and other related questions on animal behavior. Researches in this field has implications in our understanding of human evolution and in improvement of human health and well-being.