Wilderness Underfoot: The mystery of sleep, Part 2

StoryImage( ‘/Images/Story//Auto-img-116361833922729.jpg’, ‘Image provided’, ‘Our most common rabbit – The eastern cottontail sleeps about nine hours a day.’);
StoryImage( ‘/Images/Story//Auto-img-116361837832461.jpg’, ‘Image Provided’, ‘A long sleeper – The eastern gray squirrel sleeps about 18 hours a day.’);
StoryImage( ‘/Images/Story//Auto-img-116361843722729.jpg’, ‘Image provided’, ‘One of the longest sleepers – The little brown bat spends 20 hours a day sleeping, hanging upside down the entire time.’);
StoryImage( ‘/Images/Story//Auto-img-116361824418314.jpg’, ‘Image Provided’, ‘The only North American marsupial – The opossum is nocturnal, sleeping about 18 hours a day.’);
StoryImage( ‘/Images/Story//Auto-img-116361820517740.jpg’, ‘Image Provided’, ‘Sleeping while standing – Horses and cows can sleep on their feet. Horses sleep four hours, while cows sleep three hours.’);
StoryImage( ‘/Images/Story//Auto-img-116361828617740.jpg’, ‘Image Provided’, ‘An annoying pest or a favored pet – The mouse is nocturnal, sleeping about 12 hours a day.’);
StoryImage( ‘/Images/Story//Auto-img-116361816815919.jpg’, ‘Image provided’, ‘Even invertebrates sleep – Researchers have studied the brain waves of arthropods such as crayfish, fruit flies, bees and paper wasps. They’ve found that all these creatures go through sleep cycles, and in tests where they were sleep-deprived, they made up for it with longer and deeper sleep cycles the next opportunity they had to rest. ‘);
StoryImage( ‘/Images/Story//Auto-img-116361841015919.jpg’, ‘Image Provided’, ‘With open eyes – Like many other fish, the catfish is a “bottom sleeper,” holding on with its fins. Scientists have measured the brain waves of sleeping catfish.’);
StoryImage( ‘/Images/Story//Auto-img-116361813421895.jpg’, ‘Image provided’, ‘The common barn swallow.’);

Most of what we know about sleep has come from animal studies.

When it comes to solving the mystery of sleep, scientists first need to define what they mean by the term. They’ve generally agreed that sleep involves: little movement; a typical sleeping posture; reduced responsiveness to stimulation; and quick reversibility (a sleeping creature can be re-awakened). Even with this set of criteria, the function of sleep may be entirely different from one creature to the next—and whether it involves physical rest, the brain’s rewiring of memories, dreaming or some other process, is not always clear.

Oddly, researchers have discovered that some animals sleep on one side of the brain at a time, often with one eye open. This occurs for animals such as dolphins and whales, which must occasionally rise to the surface of the water to breathe, and for animals such as ducks and pigeons, which are often under risk of predation. Researchers suspect that migratory birds, such as swallows and swifts, sleep this way while migrating over the ocean.

Other interesting facts about sleep in animals found in our region:

From the Nov. 15-21, 2006, issue

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