How does sleep affect performance

DLR study on lack of sleepHow fatigue reduces performance

Johanna did it for science, for eleven days and nights: "I slept like a baby because it was also extremely dark and there were no noises. And that is less common at home."

At the German Aerospace Center (DLR), the test person visits the laboratory again, where she took part in a sleep study in December. The place looks like a hospital room: completely white, a trundle bed with pedal levers. The light can be dimmed.

In the research facility envihab, the behavior of the study participants was strictly monitored in order to determine the risks from insufficient sleep to chronic sleep deprivation.

"So I always had to do my performance tests on the computer. Otherwise, I didn't spend that much time in here because we shouldn't be in the rooms between the individual examinations and the tests, so that we can always ensure that we don't fall asleep in between . "

Up to 38 hours without sleep

Under constant observation, without daylight, with several medical tests during the day and wired at night: at the end of the study, the 36 test subjects should each have lived and slept for eleven days. Their data will be used to research how lack of sleep affects performance.

Half of the participants are allowed to sleep eight hours per night, the other half only five hours each night. This means that they are exposed to chronic lack of sleep. After a night of rest, all test subjects are faced with the most tiring part of the study:

"The most exhausting day was definitely the one with the 38 hours of sleep deprivation. So going through the night wasn't that bad. But then early in the morning during this cognitive performance test I noticed that it was really super difficult to stay awake, that was really hard . "

Adenosine makes you sleepy

Johanna even slept eight hours every night. Doctoral student Denise Lange is accompanying the study at the Institute for Aerospace Medicine. The aim is to compare Johanna's group with the subjects with chronic sleep deprivation.

"We have three key points: that is after the chronic phase. Let's see what is the relationship between the experimental and control group? Are these eight hours in the experimental group enough to bring the test subjects back to the level of the control group? Then Acute sleep deprivation: Does the subject who was in the experimental group cope with it just as well, although they have a history of chronic sleep deprivation as the subject who was in the control group and was allowed to sleep for eight hours at all? "

In order to compare the groups, the scientists use many tests and measurements to determine how tired and productive the test subjects are. She is particularly interested in the adenosine molecule. It is associated with the self-regulation of sleep - called homeostasis - in the brain:

"In the homeostatic process, it is assumed that adenosine plays an important role in this: It accumulates in the brain over the course of the day, docks at the receptors and makes us tired. Caffeine is exactly the opposite of this. Acutely we already know a lot about it. Where the model doesn't quite work anymore is with chronic sleep deprivation. And that's exactly what we're investigating here. "

How Much Sleep is Enough?

In order to make visible how many receptors in the brain are occupied with adenosine - i.e. how tired the test subjects are - recordings are made in the positron emission tomograph. Like all other measurement results, these brightly colored images of the brain are intended to help understand how chronic sleep deprivation affects people.

There are no results yet, because the study at DLR will run until mid-February. However, just by participating in the experiment, Johanna was able to draw her own conclusion:

"I've found that getting enough sleep is really extremely important. I've tried this many times before. But from everything I saw, I realized that you're not as productive as you would be if you were you have had a good rest. And I really try to make sure to actually sleep eight hours because you are more productive. "