This ‘sleep’ section is about animals that either:  1. Sleep [are inactive] in the daytime and are active at night, or the opposite, 2. Sleep at night but are active in the daytime or 3. Have shorter hibernation times.  To make this easier to understand, we will use the word torpor to show any short ‘sleep’ time.  Some sources called hibernation a winter torpor and estivation a summer torpor. 
    When an animal is in torpor, its body slows down.  Its heartbeat and temperature go down.  In ‘human’ sleep, a person can wake up instantly.  With torpor, the animal doesn’t seem to see, hear, or feel things going on around it.  It is groggy and it takes a little while for it to wake up.  This is not as deep a ‘sleep’ as hibernation and can last a very short time.
    Examples of animals that go into torpor:

     Diurnal torpor is when creatures ‘deep sleep’ for only part of a day.  The part of day depends on what animal it is.

    Examples of Diurnal torpor are:

    This kind of torpor usually happens with small animals for different reasons.  They can get their food [like insects] for only part of the day.  Since these are small creatures, they can’t eat and store enough to keep their bodies active all the time.  The animals adapt by ‘sleeping’ through the times when it would be hard to get food.  By doing this, their bodies use less energy and their food lasts longer in their bodies.  They wake up when they can get food again.
    With frogs, the air is just too cold at night.  It will go to ‘sleep’ [into torpor], its heartbeat and breathing will slow down, and less energy [food] will be needed to keep it warm.
    Most animals are in danger during torpor or hibernation.  They are so slow and unaware of what is happening around them that they are easy to catch.