New research shows that dolphins can stay awake for at least 15
days in a row without experiencing fatigue, or other negative
side effects. To put this in perspective, human research
subjects have been able to stay awake for only eight to 10 days,
and all experienced progressive deterioration in concentration,
motivation, perception and other mental processes as the period
of sleep deprivation increased. Dolphins can stay awake for this
long because they sleep with only half of their brain at a time.
This process, called unihemispheric sleep, was thought to have
evolved as a way to allow dolphins to continue breathing at the
surface while resting. Brian Branstetter from the National
Marine Mammal Foundation and colleagues studied two bottlenose
dolphins (Tursiops truncatus), one male and one female, and
found that they could use echolocation with “near-perfect
accuracy” for up to 15 days. Both dolphins showed no signs of
fatigue for five days, and the female continued other tasks for
10 additional days. “Thes