Dolphins, whales, and migratory birds sometimes have weeks when they need much less sleep than usual. False True
The correct answer and explanation is:
Correct Answer: True
Many species of dolphins, whales, and migratory birds undergo periods of reduced sleep, particularly when they are engaged in long-distance migrations or travel. For instance, during migration, birds might reduce their sleep time to conserve energy for their journey. Similarly, dolphins and whales exhibit polyphasic sleep, where they alternate between periods of rest and activity. These animals only sleep with one hemisphere of their brain at a time, which allows them to remain partially alert and continue swimming or navigating through their environment.
In the case of whales and dolphins, sleep is necessary but is not always continuous. They engage in unihemispheric slow-wave sleep (USWS), where one half of their brain remains active while the other half rests. This pattern is essential for survival because it enables these animals to maintain essential behaviors, such as breathing, swimming, and avoiding predators. This type of sleep allows them to keep moving even while getting the rest they need.
Migratory birds also face similar challenges. Their migration routes can span thousands of miles, and they may need to fly for extended periods without stopping. During these long flights, they can significantly reduce their sleep, as their survival depends on covering vast distances. In some cases, birds have been observed to engage in “sleep bouts” where they nap for short periods while flying, often utilizing one hemisphere of their brain to rest while the other stays active.
In summary, dolphins, whales, and migratory birds adapt their sleep patterns based on environmental demands, especially during migrations, requiring them to operate with reduced sleep at times.