Twenty-four hours of sleep deprivation can lead to conditions similar to the symptoms of schizophrenia in healthy persons, a new study has found.
A team led by researchers from the University of Bonn in Germany and King's College London said that after 24 hours of sleep deprivation in healthy patients, numerous symptoms were noted which are otherwise typically attributed to psychosis or schizophrenia.
"It was clear to us that a sleepless night leads to impairment in the ability to concentrate," said Professor Dr Ulrich Ettinger of the Cognitive Psychology Unit in the Department of Psychology at the University of Bonn.
"But we were surprised at how pronounced and how wide the spectrum of schizophrenia-like symptoms was," Ettinger said.
The scientists examined a total of 24 healthy subjects of both genders aged 18 to 40 in the sleep laboratory of the Department of Psychology. In an initial run, the test subjects were to sleep normally in the laboratory.
About one week later, they were kept awake all night with movies, conversation, games and brief walks. On the following morning, subjects were each asked about their thoughts and feelings. In addition, subjects underwent a measurement known as prepulse inhibition.
"Prepulse inhibition is a standard test to measure the filtering function of the brain," said lead author Dr Nadine Petrovsky from Ettinger's team.
In the experiment, a loud noise is heard via headphones. As a result, the test subjects experience a startle response, which is recorded with electrodes through the contraction of facial muscles. If a weaker stimulus is emitted beforehand as a "prepulse," the startle response is lower.
"The prepulse inhibition demonstrates an important function of the brain: Filters separate what is important from what is not important and prevent sensory overload," said Petrovsky.
In the subjects, this filtering function of the brain was significantly reduced following a sleepless night.
"There were pronounced attention deficits, such as what typically occurs in the case of schizophrenia. The unselected flood of information led to chaos in the brain," said Ettinger.
Following sleep deprivation, the subjects also indicated in questionnaires that they were somewhat more sensitive to light, colour or brightness.
Accordingly, their sense of time and sense of smell were altered and mental leaps were reported. Many of those who spent the night even had the impression of being able to read thoughts or notice altered body perception.
"We did not expect that the symptoms could be so pronounced after one night spent awake," Ettinger said.