Dr. Krop-Benesch, do you believe that sleeping outside is healthy?
Yes, if you don't get bitten by mosquitoes on vacation in the tropics, which transmit a life-threatening disease. Sleeping outside is healthy because you get plenty of fresh air. You also experience a greater temperature difference between day and night when sleeping outside. Unfortunately, this is usually different when sleeping indoors because many bedrooms are far too warm, especially in low-energy houses, which are not at all good for our sleep. What many people don't know is that a clear temperature difference between day and night is very important for our internal clock. Our internal clock primarily determines our sleep and it has hardly changed since the Stone Age because it is fixed in our genetic material.
How did our Stone Age ancestors sleep?
Our ancestors adapted to the light conditions. It was dangerous for them to be out and about in the dark, because they would have been at a disadvantage if they encountered a sabre-toothed tiger in the dark. So they went to sleep in a sheltered place at dusk.
Your internal clock has ensured that melatonin is released, and this messenger substance ensures various important processes in our body at night that are neglected during the day because the energy was needed in the light for hunting, gathering and rearing children. At night, melatonin is responsible for storing what we have experienced in the brain, for wound healing and other activities of the immune system and for the regeneration of our tissues - i.e. cell division.
So did our ancestors in Europe sleep significantly longer in winter than in summer?
No, on average they slept only 20 minutes longer on long winter nights than on short summer nights. Nevertheless, they went to bed at dusk and got up at dawn. But on long nights, they were awake in between, talked or had sex and then went back to sleep. In summer, they often continued to sleep in the light because the darkness did not last long enough for all the regeneration processes in the body to be completed.
Fresh air and sleeping outside are healthy
We know from great passion, our many years of experience and scientific findings that sleeping outside is healthy. But there are plenty of other reasons to sleep a little more unusually.
Does this mean that our current sleep rhythm is rather artificial?
Oh yes, sleeping for 8 hours straight in winter and summer is very unnatural and is unfortunately not based on our internal clock but on the 'social' clock. Especially in winter, getting up early is extremely unnatural for children - who need more sleep than adults. In Europe, 8 a.m. is the ideal time to wake up. School should not start until 9 a.m., but experts have been calling for this for a long time in vain. Incidentally, recent studies also show that people were more productive working from home during the coronavirus period than before. We attribute this mainly to the fact that they were able to sleep longer because they didn't have to travel to work.
Why do many people wake up when it gets light, even though their internal clock should let them sleep on?
Many people think that light controls our internal clock. But that's not true. Otherwise we could fall asleep in a dark room at any time. Incidentally, jet lag is the best proof that light does not play the decisive role, but rather our internal clock stored in our genetic material, which only changes slowly after a quick trip to the east or west. We chronobiologists interpret waking up in bright light as the result of an expectation.
If you are convinced that you cannot sleep in the light, you will wake up when it gets light. However, if you accept this and have experienced a few times that you can continue to sleep in the light even in summer, you will continue to sleep in the light after a few nights. The body is happy because it has enough time to regenerate. By the way, it's the same with noises. If you get involved, you won't be woken up immediately by birdsong early in the morning. The body knows that songbirds are not a threat, whereas you would naturally wake up sooner to the loud, aggressive barking of a dog.
What influence does artificial light have on our sleep?
Artificial light disturbs the human sleep rhythm. Really bright light in the home has only been around for about 100 years. Before that, people only knew dim candlelight and the yellowish light of a fire. This is why artificial light irritates our melatonin secretion and thus our day-night rhythm, and it is the same with animals. Incidentally, children are particularly affected. They need a lot of sleep, produce a lot of melatonin and are particularly sensitive to disturbing light, such as the streetlights outside the window. That's why I and many like-minded people are campaigning against light pollution. A lot could be done here with simple measures.
Can you imagine that sleeping outside can be used for medical purposes?
Yes, it can certainly help to restore the natural sleep rhythm, because sleeping outside - without disturbing artificial light, of course - provides unlimited fresh air, the natural temperature difference between day and night can be felt and the dawn can be experienced in the evening and morning. An intact sleep rhythm makes you physically and mentally fit! People with sleep disorders would therefore certainly benefit from sleeping outside, as would spa and burn-out patients, because they are taken out of their usual stressful environment. I can even imagine that people in old people's homes would at least get some fresh air at night.
Thank you very much for the very informative interview!
About the person:
Dr. Annette Krop-Benesch is a chronobiologist, i.e. an expert on the internal clock of living beings. She is particularly interested in the effect of light and darkness on nature and health.
I conducted the interview with her by telephone and as part of the European Symposium on the Protection of the Night Sky in Fulda.
