Does everyone need eight hours of sleep? And how bad is a night without sleep? We sleep approximately a third of our lives, which is a very strange state of being, seen from an evolutionary point of view. “During sleep you can't eat and you can't reproduce. Moreover, while sleeping you are an easy prey. Nevertheless, sleep occurs in (almost) the entire animal kingdom, in all kinds of different forms”, states Van der Meij.
As research techniques became more advanced, sleep research has taken off in the last ten years. Van der Meij: “We can gain knowledge about all kinds of animals, from octopuses and jellyfish to flatworms. The variation in sleep is enormous. Some animals sleep two hours a day, others fourteen.” The increased research opportunities provide new knowledge and new questions about the functions of sleep. For example, scientists discovered that REM sleep, the sleep phase in which humans usually dream, also occurs in reptiles. While they observed this with one lizard species, REM sleep remarkably did not occur in a related species.
Unnatural light
Humans share similarities with birds when it comes to sleeping. “Both species go through the same sleep stages. At the same time, some cognitive processes that take place during sleep seem to be very different.” In contrast, birds that live both on land and over the ocean, have quite a different sleep routine. On land they sleep a lot, but while flying over ocean they can manage several days with hardly any sleep. And if they sleep for a bit, they do so while flying. It's fascinating how many solutions have emerged in evolution to aid the need for sleep. Over time human sleeping patterns have changed as well. 'Among indigenous peoples, living without electricity, sleep coincides much more with the natural light/dark cycle. Now that we use so much unnatural light, our sleep rhythms are also different.'
Casual sleepers
A commonly heard statement about human beings is that they need to sleep eight hours a day, but that’s not quite true. “For some people eight hours are desirable, but for others six hours a day is enough”, emphasizes Van der Meij. Scientists are still unsure about the exact health effects of sleep, but they agree that chronic lack of sleep is disastrous. “It isn’t that much of a problem to pull an all-nighter once in a while, but sometimes people are a bit too casual when they say that they'll catch up on their sleep later. Sleep is a fundamental part of our existence, but sometimes we don’t treat it serious enough,” says Van der Meij.
Nevertheless, she does not want to be preachy about the importance of sleep. She prefers to show what an interesting phenomenon she is studying. “So many things happen when we sleep. Our research is like a puzzle that becomes more complex and more beautiful with every piece we find.”
Science Café Nijmegen
Date: 19 april, 19:30-22:00Location: The Shamrock / Smetiusstraat 17 NijmegenTickets: Free. You don't have to register.
Photo: Yehor Tulinov via Unsplash