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A study conducted by researchers in the US found that losing just one hour of rest could kill people's desire to help others, even relatives and close friends. The team noted that a bad night appeared to dampen activity in the part of the brain that encouraged social behaviour. "We discovered that sleep loss acts as a trigger of asocial behaviour, reducing the innate desire of humans to help one another," said Prof Matthew Walker, co-author of the study at the University of California. "In a way, the less sleep you get, the less social and more selfish you become."
The researchers suggest that a chronic sleep deficit could harm social bonds and compromise the altruistic instincts that shape society. "Considering the essentiality of humans helping in maintaining cooperative, civilised societies, together with the robust erosion of sleep time over the last 50 years, the ramifications of these discoveries are highly relevant to how we shape the societies we wish to live in," said Walker.
The team examined the willingness of 160 participants to help others with a "self-reported altruism questionnaire", which they completed after a night's sleep. Participants responded to different social scenarios on a scale from "I would stop to help" to "I would ignore them". In one experiment involving 24 participants, the researchers compared answers from the same person after a restful night and after 24 hours without sleep. The results revealed a 78% decline in self-reported eagerness to help others when tired.
(Sascha Pare. www.theguardian.com 23.08.2022. Adaptado.)
In the excerpt from the first paragraph "sleep loss acts as a trigger of asocial behaviour", the underlined expression means
