It鈥檚 a challenge that most of us have faced when up against an essay deadline, a late-night crisis in the office or perhaps a long car drive. Just how long can we push ourselves mentally before our brain needs a break?
For people in jobs where concentration is critical, like truck drivers, power-plant operators or airline pilots, a 12-hour shift is the limit for most. But pity doctors: complex surgery can go on for hours longer than that, although the lengthiest operations tend to be shared by more than one team.
Until 2004, doctors in the UK on weekend shifts used to work from Friday morning to Monday evening 鈥� that鈥檚 80 hours in total. At best they would snatch a few hours of sleep; at worst, none at all. 鈥淵ou could be working the vast majority of that time,鈥� recalls Helen Fernandes, a neurosurgeon at Addenbrooke鈥檚 Hospital in Cambridge, UK.
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Our powers of concentration decline as the hours tick away. We become less efficient, and take longer to make decisions and to sound the alarm when things go wrong. 鈥淰igilance is one of the areas most sensitive to fatigue,鈥� says neuroscientist David Dinges at the University of Pennsylvania in Philadelphia.
Dinges鈥檚 team used MRI to study the brains of people doing a vigilance task. As people鈥檚 reaction times slowed, . Dinges found that performance in the test could be predicted from the level of blood flow in the subjects鈥� right fronto-parietal network.
Read more: Maxed out: Testing humans to destruction
