The activity of the human body is largely determined by its characteristic chronotype - the most comfortable cycles of sleep and wakefulness for it. Two chronotypes are usually distinguished: "owls" and "larks". The first ones get up early and go to bed early. The latter, on the contrary, go to bed late and get up late. At the same time, many studies indicate that the former feel more energized during the day, while the latter are more prone to fatigue and stress. Changing your chronotype without medical or therapeutic intervention is quite difficult, but scientists from the Universities of Birmingham and Surrey in the UK and Monash University in Australia say they have found a way to change a person's chronotype as gently as possible by changing their daily routine in just three weeks.
According to the researchers, this change in daily routine and lifestyle helped the "owls" get up and go to bed earlier, as well as improved their emotional state and cognitive abilities. The findings of their study are published in the journal Sleep Medicine.
How to turn from an "owl" into a "lark"?
Scientists invited 22 volunteers to take part in the experiment, adhering to a nocturnal lifestyle, but not having neurological disorders and diseases associated with sleep disorders. Before starting the experiment, the researchers took tests from the participants, and also familiarized themselves with their lifestyle. Then the people were divided into two groups. One of them was given instructions to change their daily routine and lifestyle, which they had to follow for three weeks. The instruction was as follows:
- Getting up 2-3 hours before your usual time and increasing exposure to daylight in the morning;
- Go to bed 2-3 hours before the usual time and limit exposure to lighting in the evening;
- Compliance with the same duration of sleep on workdays and weekends (maximum deviation from the schedule by 15-30 minutes was allowed);
- Regular meals and early tomorrow (immediately after waking up), lunch at the usual time and dinner no later than 7 pm;
- Reducing caffeine consumption after 15:00;
- Refusal from daytime sleep after 16:00;
- Transferring regular physical activity to the morning hours (if any).
Compliance was monitored using activity trackers, as well as personal diaries, in which participants recorded the time of going to bed and getting up, eating, exercising and drinking coffee. In addition, before and after the experiment, the participants were asked to fill out questionnaires, with the help of which scientists determined their emotional state, as well as to take tests on reaction, attention and physical strength (grip strength in this case). The group that was not given instructions on how to change their daily routine had to adhere to their usual lifestyle.
The researchers report that in a three-week experiment, participants who adhered to the prescribed instruction were able to successfully shift bedtime by an average of 1.73 hours and wake-up time by 1.92 hours, with no change in sleep duration. … In addition, those living on the new routine were able to shift the timing of food intake for three weeks.
Scientists also noted a decrease in depression and stress scores in people who adhered to the instructions of the new daily routine. According to the analysis of polls, the first fell by 3.2 points, the second - by 3.8 points. In the experimental group, people in the morning hours also decreased sleepiness, improved indicators of physical strength, and cognitive abilities compared with the indicators before the experiment. In the control group, no significant changes were observed.
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The authors of the study believe that their strategy of short-term changes in daily routine and lifestyle can effectively tune the chronotype to a more appropriate one to maintain socially acceptable. At the same time, experts explain that after the experiment, the result of consolidating the new daily routine of its former participants was not evaluated. This requires more long-term research, scientists say.
Nikolay Khizhnyak
