What determines whether you are a morning or an evening person? “This is mainly due to our biological clock,” says chronobiologist Marijke Gordijn. “It is located in our brain and consists of a hundred thousand cells that generate a rhythm with a period of approximately 24 hours.”
These ‘clock cells’ tell us when it is time to go to sleep and prepare the body accordingly. “They do this by controlling all kinds of physiological processes in the body, for example by lowering our body temperature and producing melatonin. The opposite happens towards morning.”
The fact that this biological clock does not tick in the same way for everyone means that one person is active in the morning and the other in the evening. Gordijn: “Morning people walk fast on average, sometimes even with a period shorter than 24 hours.” In evening types it ticks slower, sometimes up to 25 hours. “With a fast running clock, you go to bed early and get up early. If he walks slower, he tells you to go to bed relatively late and get up late.”
Light can influence how fast or slow our biological clock is. “In addition to light-sensitive cells for vision, our retina also contains cells that are sensitive to cyan-blue light.” These cells transmit this light to the cells of your biological clock and thus tell you: it is daytime. “This way they can, as it were, turn the clock, speeding it up or slowing it down if necessary.”
Morning person superior, evening person lazy?
So it is in our nature to have different rhythms, but the morning person is especially praised in modern Western society. Successful CEOs tell anyone who will listen that they have been working hard for a long time when the rest of society is still listening. Several productivity gurus base their model for a successful day on getting up very early. Preferably before 5 o’clock, if you really want to make something of your day and therefore your life.
The evening person is left behind. Waking up late and going to sleep late is associated with laziness and a lack of self-discipline. Anyone who gets up late is ‘rotting in his bed’. Is there some truth in that? Is being a morning person really ‘better’ or healthier?
‘Don’t suddenly change your sleep rhythm at the weekend by going to bed later and sleeping in’
Niki Antypa, professor of psychology at the University of Leiden, focuses her research on the chronobiology of depression and suicide. “We know from research that evening people are at higher risk for symptoms of depression.” Other studies show that evening owls are also at higher risk for diabetes and cardiovascular disease.
But that doesn’t necessarily mean that being an early bird is healthier, or that staying up late makes you depressed. “We see that evening types more often have habits such as drinking alcohol and smoking. This means they have an increased risk of those conditions, not so much because they are evening people.”
Don’t sleep in too late on the weekend
Whether you prefer to be active in the evening or in the morning: according to experts, a regular sleep rhythm is the healthiest. An English study showed that a regular sleep-wake rhythm is even a better predictor of longevity than sleep duration. Gordijn: “So, if possible, don’t suddenly change your sleep rhythm during the weekend by going to bed later and sleeping in. Then your biological clock gets confused.”
The best way to maintain regularity in your sleep rhythm: use light. During the day, according to Gordijn, our brain needs at least two hours of direct daylight to keep its biological clock sharp. “The contrast between day and night must be clear. When you are outside in the sunlight, the light intensity is 100,000 lux, on a really cloudy day it is 10,000.”
Indoors, the light intensity is often only 100 lux at most. “Seeking daylight outside every day helps your biological clock maintain a good sleep rhythm and ensures that you do not wake up or wake up less often during the night.”
Natural rhythm continues to pull
What time we have to get up is not always entirely up to us: if you are the parent of young children or you work early shifts, it would be nice if you could transform yourself into a morning person. According to Gordijn, this is possible, to a certain extent: “It is difficult, because if you are naturally a night person, your clock keeps pushing you internally to a later rhythm. You also see that evening people, for example because they have children, become more of a morning person, and that they regain their own rhythm as soon as the children leave home.”
‘If you eat late at night, your body has to process that food and cannot relax’
If you want to have less difficulty in the mornings as an evening person, keep to a strict daily schedule, she advises. “Provide a lot of light exposure in the morning and little light in the evening. If you continue to do this, you may not become a real morning person, but you will certainly become an ‘earlier’ person.”
Pay attention to the time you eat your dinner, says Antypa. Nutrition and when we eat have a major influence on your biological clock. “If you eat late at night, your body has to process that food and cannot relax. Your body gets confused and thinks it’s daytime.”
In the Low Countries many people have dinner around six o’clock. For example, are Italians and Spaniards disrupting their own biological rhythm with their generally later dinner times? Antipa, herself Greek: “We often eat a heavy meal in the evening and usually have a snack later in the evening. In southern countries the emphasis is on lunch. In the evening they don’t eat until around eight o’clock, but it is light: often only some leftovers from lunch. Then your body doesn’t have to work so hard in the evening to digest everything.”
Going to bed earlier can be difficult for inveterate evening people – there is always another episode of that one series to watch – but it is necessary to advance your biological clock. “Being a night person is also a matter of behavior,” says Gordijn.
“Because you are up late and sitting in the light, for example behind your computer, this light tells your biological clock: it is still daytime. If you sleep in in the morning, you still have your eyes and curtains closed when the sun starts to shine, so your biological clock thinks it is still night and time to sleep. He will only get later.”
