“We should take a more relaxed approach to sleep”

ETH News: Ask around and you¡¯ll find that almost everyone has trouble sleeping. Is it really such a big issue, or do we simply enjoy complaining?
Caroline Lustenberger: If I dismissed sleep problems as mere complaining, we wouldn¡¯t be having this interview (laughs). For me, it¡¯s a problem because sleep disorders are associated with a high level of suffering. Sleep is essential for human beings and yet more than a third of people in Switzerland report experiencing moderate to severe problems with their sleep.

Have these problems become more common?
Self-reported sleep problems have increased sharply since 2012. The Swiss government collects data every five years with surveys. The latest figures are the highest they¡¯ve been since the survey was first conducted in 1997. Since the last survey in 2017, percentages have risen further, particularly among young people and women.

What kinds of sleep disorders are we talking about?
The most common sleep disorders in Switzerland are insomnia, sleep apnoea and restless legs syndrome. Insomnia is characterised by problems falling or staying asleep and is often caused by stress in our daily lives. Sleep apnoea, which is characterised by breathing being regularly interrupted during sleep, is often linked to lifestyle and is exacerbated by factors such as obesity. Some people also have restless legs syndrome which causes them to feel an unpleasant urge to move their legs and therefore cannot find rest. Each of these issues requires a different approach or therapy. These disorders require different approaches or therapies. For sleep apnoea, special breathing machines are commonly used, and lifestyle adjustments, such as weight loss, can be very effective. Cognitive behavioural therapy is often the first choice of treatment for insomnia. Most people who seek help and find a solution significantly improve their quality of life.

How do you explain the increase in cases?
Sleep problems and disorders have many causes. Key factors that have become increasingly apparent in recent decades are the constant pressure to perform, a lack of boundaries and the effects of digitisation. As a result, many people¡¯s working days intertwine with their private lives and they lose that clear separation that comes from properly ¡°finishing work for the day¡±. Stress and pressure are considered the greatest obstacles to a good night¡¯s sleep. Stressful events such as wars, the coronavirus pandemic or uncertainties about the future intensify this state. For many of us, our thoughts start racing as soon as we get into bed. That makes it difficult to let go. People remain in a state of hyperarousal, inner tension and constant stress. Obesity and an increasingly sedentary lifestyle are also becoming more prevalent and are contributing to the increase in sleep disorders.

You¡¯ve just written a popular guide to sleep with your colleague Salome Kurth at the University of Freiburg. What motivated you to do this?
On the one hand, we wanted to clear up misconceptions about the topic of sleep, and on the other hand, summarise new scientific findings. Through this clarification of the state of knowledge, we also wanted to relieve people of the pressure to sleep perfectly in order to avoid becoming ill. In researching for the book, we repeatedly saw how much of the information out there emphasises how important sleep is and that a person will get ill if they don¡¯t get enough of it. While that¡¯s certainly true in the long run, I also think it creates a lot of pressure: people are afraid of sleeping poorly or not ¡°perfectly¡±, which, paradoxically, can actually cause problems with sleep.

And your book offers a counterbalance.
Exactly. In our book, we show how individual sleep is. Even aging changes sleep: the older you get, the less deep your sleep becomes and the more often you wake up at night. Some of these factors are beyond our control. They are part of our biology. What is important here is to cultivate a sense of calmness. Short-term sleep problems are common and relatively unproblematic. Our body has a remarkable ability to regulate itself to a certain extent. We want readers to accept this and, in doing so, feel permitted to relax more. However, we also emphasise that there are factors you can influence to improve your sleep, and the book helps readers understand which factors these are and how we can take control over them.

What factors are you referring to?
There are many, but for example, a relaxed attitude and a willingness to let go are often the key to easing milder sleep problems. Anyone experiencing persistent and severe problems should seek professional support.

What kind of lighting helps you to sleep better?
Bright light during the day and when you get up is ideal. Exposure to bright light in the morning helps you get going faster. In the evening, you should use dim and warm light and avoid bright screens or harsh lamps. That said, there are significant individual differences in sensitivity to light and some people can fall asleep even under the brightest light conditions. If you have to get up briefly during the night, you shouldn¡¯t switch on a bright light. I recommend small LED candles that give off a warm light instead.

What new findings from sleep science have you incorporated into your book?
One of the new topics is how people perceive their own sleep. Research shows that sleep problems have a lot to do with how you think about and are attuned to your own sleep. Other topics include digitisation and sleep tracking. Sleep trackers can relieve people who worry excessively about their sleep, as they often reveal that they are getting more sleep than they think. However, the role of these devices is ambivalent: it is crucial that they do not create additional pressure, as the accuracy and reliability of these devices and their measurements vary greatly. This can lead to misinterpretations and increased stress. People start having problems that they wouldn¡¯t have had without these devices. In fact, more and more people are developing an obsession with perfect sleep, something known as orthosomnia. That¡¯s why it¡¯s important to treat the results of trackers with a healthy dose of scepticism and not to let them completely define you.

What aspect of sleep has seen little research to date?
There are still many unanswered questions around sleep. For example, we still don¡¯t entirely understand all the different functions that sleep serves or which aspects of sleep support which bodily functions. Sleep is not a uniform process ¨C it goes through different stages, characterised by different brain waves. Our research aims to better understand the characteristics and functions of these stages. We also want to find out how sleep is related to various different diseases. For example, there¡¯s evidence that sleep is related to cardiovascular disease, immune disorders and Alzheimer¡¯s. There have been some other interesting new findings too: it has been shown that sleep happens differently in individual parts of the brain. What that means is that when we sleep, our brain does not experience that sleep to the same extent everywhere. Research is currently being conducted into why some areas of the brain sleep more deeply than others. Every new insight can help us develop methods to better understand, improve, and normalise sleep in cases of irregularities ¨C and thereby promote long-term health.

Which of the tips and tricks in your book do you use when you can¡¯t get to sleep or have trouble staying asleep?
For me, it¡¯s clear: good sleep starts during the day, and I try to structure my day in a way that helps me sleep better at night (e.g. exercise, plenty of light during the day, switching off in the evening).  Additionally, many people are probably unaware that regulating body temperature has a significant impact on both falling asleep and staying asleep. That means it¡¯s important to have warm hands and feet and to allow your core body temperature to drop in order to initiate sleep. If you have cold hands and feet, a warm shower before going to bed can help.

When I have a bad night¡¯s sleep, I start obsessing and the same thoughts keep going round and round in my head. What would you advise?
In cases like that, you can try to actively let go of your thoughts. For instance, I imagine packing each thought into a balloon and letting it float away. Sometimes it also helps me to write down all my negative thoughts before going to bed. Then I say to myself: I¡¯ve thought about this enough, I can think about it again tomorrow. When something¡¯s weighing on my mind, I shift my focus to positive things and consciously list the things that were good and that I¡¯m grateful for. Then I choose the best one for myself. Breathing exercises can also help. I just have to do something monotonous that doesn¡¯t get me worked up. I also trust my sleep to regulate itself. If I don¡¯t sleep well one night, I look forward to the next because I know that I will sleep more deeply and more soundly because my sleep pressure is higher.