There are different types of people. The ones who go to bed and rise early and the ones who stay up late and like to sleep until late. “Larks” and “night-owls”. But is any type better or worse? Do night-owls get too little sunlight? How about sleeping little during the week and catching up on sleep during the weekend? That is possible, right?
The answer is yes. It is actually possible to catch up on sleep. To find out why it isn’t the most advisable thing to do though, continue reading.

The basics
Ok, let’s start off at the beginning: What is a chronotype?
Chronos, as you may know, is the Greek God of time. Thus, Chronotype is a distinction made between people concerning their personal time patterns. Humans are diurnal creatures (although this might seem different in a club on Saturday at 4a.m.) and our brains are all tuned in to daytime when we feel fresh and energetic and nighttime when we get tired and fall asleep.
Turning the clock upside down
This pattern can of course be turned around. We can get accustomed to being awake at night and sleeping during the day. The problem is that this is unhealthier than previously thought: Sunlight lets us produce vitamin D, which is important for the production of serotonin and dopamine.
But studies show that ignoring our so called circadian rhythm brings more trouble than just the lack of Vitamin D: All our bodily functions are in synch with the day-night circle. That means that even if we are used to being up at night and sleeping during the day, our body is still running in standby-mode at night. Our body temperature, ability to focus, immune defense and even our mood is tuned to being low when the sun is not up. Mistakes and even deadly incidents at work are significantly higher at night than during normal working hours.
Larks and Night-Owls
So what about people who tend to stay up late and sleep in? Are they doing something wrong? Is it in every human’s nature to be up when the sun rises?
The answer is NO.
As determined by their genes, humans have different inner clocks. A tiny patch in our brain called the suprachiasmatic nucleus (SCN) recognizes time through its interactions with light-responsive cells in the back if the eye.
Humans can be divided in two groups: Larks and owls. Larks tend to have a slightly faster inner clock, owls a slower one. Larks get tired quite early in the evening and are happy to jump out of bed in the morning, owls are the opposite. No type is better than the other: But sticking to your personal schedule could be important.
Sticking to your schedule
As the guardian reports, a study of undergraduates showed that keeping a regular bedtime has a positive effect on the quality of sleep even if the overall amount of sleep was roughly the same. The subjects who went to bed at different times showed poorer academic performance. That means that building up sleep deficit over the week and catching up on weekends may be fine for the total amount of sleep but bad for its quality. Unfortunately, a huge number of people are affected by so-called social jet lag. Going to parties late, working early, sleeping until noon on Sunday, in short, constantly being “out-of-synch”. According to research of the University of Arizona College of Medicine, this causes sleepiness and fatigue, increases the risk of cardiovascular diseases and, quite simply put, really bad mood.
Knowing your chronotype
The good news is that a team of German scientists around Achim Kramer have found a method to identify a person’s individual chronotype. Out of 20.000 genes they have identified 12 relevant ones that determine whether someone is a lark or an owl and what the person’s individual time is. This may be important for determining the best time to administer medicine and to reduce side-effects.
If you are not in the need of medication, this may not be relevant for you. You most likely know that type of person you are since a long time anyway. Stay true to yourselfand your needs, listen to your body and you’ll be fine.