Good sleep is crucial for our physical and mental wellbeing. Researchers from Fribourg have shown that sleep can be made worse by using willpower.

Sleep is influenced by biological factors (e.g. circadian rhythm or homeostasis). At the same time, psychological factors also influence our sleep. We often wish that we could simply fall into bed after a stressful day in order to sleep deeply and soundly. Unfortunately, this wish often remains unfulfilled and, despite our desire to have a really good night’s sleep, we find it difficult to achieve the well-earned rest we long for.

Sleep researchers at the University of Fribourg have now confirmed the existence of this particular phenomenon: in a study just published in the journal «Nature and Science of Sleep», they have demonstrated that intending to sleep better does not lead to better sleep. At the same time, however, it is possible “that we can make our sleep worse by using willpower and that intending to have worse sleep can lead to poorer sleep quality,» says PhD student Selina L. Combertaldi, who carried out the study at the Department of Psychology of the University of Fribourg within the ERC project «MemoSleep» led by Prof. Björn Rasch (see box below).

Deducing sleep quality from brain waves
To measure sleep objectively, the electrical activity of the brain is measured with an electroencephalogram (EEG). The study focussed specifically on the quality of sleep as a whole: how long it took to fall asleep, the quantity of deep sleep as well as the number and duration of waking phases during the night, all of which are made visible by the EEG. At the same time the subjects were asked how they had slept the previous night and these subjective values were compared with the objective measurements.

The Unifr study involved 22 healthy young sleepers who spent three nights in the sleep laboratory. Before falling asleep, the participants were told that they were to sleep «as well as possible» or «as badly as possible» or «as normal» that night. How to achieve this was left up to each person to decide for themselves.

Respondents wake up more often if they intend to sleep worse

Sleep researchers Selina L. Combertaldi and Björn Rasch were able to prove that the intention to sleep worse increases the time taken to fall asleep by a factor of more than two. As well, the participants managed to increase the number of awakening responses during the night by about 70%, even though they were not actually awake longer during the night. The subjects were thus able to significantly reduce the objectively measurable quality of their sleep.

Moreover, the objective measurements showed that by using their willpower they were not only able to adversely affect their sleep and sleep quality, but also their subjective assessment the morning after. The participants estimated that they could deliberately delay their falling asleep by significantly more than a factor of three. And the next morning they assessed the quality of their sleep as significantly worse. Their perceived deterioration in sleep was much greater than the objective measurements were able to indicate.

«The results can be of central importance for a better understanding of how sleep problems arise. In this study, we were able to demonstrate for the first time that poor sleep can even be induced in healthy individuals and this by willpower alone. Our test subjects exhibit the same pattern as people with sleep disorders: subjectively, poor sleep is greatly overestimated compared to what can in fact be shown objectively,» says psychologist Selina L. Combertaldi.

• Literature: Combertaldi SL, Rasch B. Healthy Sleepers Can Worsen Their Sleep by Wanting to Do so: The Effects of Intention on Objective and Subjective Sleep Parameters. Nat Sci Sleep. 2020;12:981-997. Date of publication: 11.11.2020
• MemoSleep: The ERC Starting Grant “Longing for a good night’s sleep: A memory-based mechanism to improve sleep and cognitive functioning (Acronym: MemoSleep)” is led by Prof. Björn Rasch of the University of Fribourg. The aim is to find out how psychological concepts activated before sleep can influence objectively measurable sleep and thus to find ways to help people with stress-related sleep disorders or to help (older) people find restful sleep without medication.