如果你周一早晨醒来觉得头脑不够清醒敏锐，多半是因为周末没有得到足够的休息。科学家发现，周末睡懒觉不是懒散放任，它可能对健康至关重要。研究人员对志愿者的测试显示，偶尔睡懒觉是抑制因睡眠影响健康的重要的“解毒剂”。

    Scientists have discovered that an extra dose of sleep is more than just a luxury -- it provides an essential boost to brain power ahead of the working week. 

    Those who return to work on Monday morning refreshed from a long rest the day before perform better than those who spent less time in bed at the weekend, according to a study published in the journal Sleep.

    A single long rest session is all that is required to replenish the brain and boost energy, alertness and attention span after a week of restricted sleep, the study showed. Even 10 hours in bed may not be enough to restore those who regularly burn the candle at both ends, so they should rest even longer. 

    The scientists also warned against staying up all night partying at the weekend, which they said could significantly impair a person’s performance at work the following week. 

    The study was led by David Dinges, chief of the Division of Sleep and Chronobiology at the University of Pennsylvania. “The additional hour or two of sleep in the morning after a period of chronic partial sleep loss has genuine benefits for continued recovery of behavioral alertness,” he said. “The bottom line is that adequate recovery is important for coping with the effects of chronic sleep restriction on the brain,” he added.

    The scientists conducted a sleep deprivation experiment on 159 healthy adults, with an average age of 30. Participants were asked to complete 30-minute computerized assessments every two hours. Those whose sleep had been restricted were found to have a shortened attention span, impaired alertness and reduced reaction time. Their normal functions were restored after just one full night of sleep. 

    The study also showed that people who got no sleep at all after the period of sleep deprivation performed significantly worse than normal. “This highlights the importance of avoiding all-night sleep deprivation following a period of restricted sleep,” said Mr. Dinges.