Lack of sleep makes it more difficult to adapt to unexpected and threatening stimuli, thus triggering anxiety. You become hyper vigilant, but it used to be an advantage.
Those who suffer from anxiety may have difficulty falling asleep, but the opposite also happens: when you sleep little you tend to become more anxious. Why does this happen? According to a new study posted in pre-publication on the server bioRxivlack of sleep makes it more difficult for the brain to adapt to new and potentially threatening elements of the surrounding environment.
The result? We are more alert and guarded, constantly on tenterhooks. From an evolutionary perspective it makes sense: for our ancestors, vulnerable to predators, this state of heightened alert was often advantageous. Today, safe in our homes, we see above all the disadvantages: the lack of sleep makes us anxious and insecure.
The threats of virtual worlds
A group of scientists from the University of Melbourne, Australia, recruited 54 healthy adults between 18 and 30 years old with no sleep or attention problems, and no psychiatric or neurological disorders. Half of the participants had, for the sake of science, to stay awake for an entire night; the other half were able to sleep for 8 hours in the laboratory. Sleep enjoyed or missed was tracked by wearable monitoring devices.
The next day, all the volunteers were led on a virtual walk between two immersive scenarios: a first neutral situation, with a well-lit office and quiet music, alternating with a more sinister environment, a dark basement where they had to collect lanterns while crying, footsteps or whispered words were heard.
Virtual reality was used to allow the study of hyper-vigilance over a prolonged and continuous period of time: other studies before now had measured this state by subjecting subjects to single threatening images, a type of stimulus which, however, is rarely encountered in real life.
Rested and adaptable
Upon entering the basement for the first time, all participants showed increased levels of anxiety, measured through heart rate and changes in hand sweating. However, when it came to entering that environment for the second time, those who had slept managed to adapt, with a reduction in stress; those who had been deprived of sleep remained as agitated as the first time.
“Sleep deprivation can cause a state of hyper-vigilance which, if it becomes chronic, can take the form of pathological anxiety,” explains Emma Sullivan, a psychologist at the University of Melbourne who led the study.
The scientists then measured how the body coped with this state of increased anxiety due to insomnia.
Those who had greater heart rate variability, i.e. a heart capable of correctly adapting to external stimuli and stress management, changing interval from beat to beat, reported that they did not feel particularly anxious in the more hostile virtual environment.
On the contrary, those who had lower heart rate variability, and therefore a less “flexible” and adaptable heart, in poorer health, reported higher levels of anxiety.
Naps chase away anxiety
Compensating for little sleep at night could therefore reduce levels of anxiety perceived during the day. In cases where insomnia cannot be resolved, for example because it is induced by night shifts or the presence of young children, naps taken during the daytime could alleviate the situation. Making us more rested and less suspicious.
