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Slide 1

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Evolutionary Theory…read more

Slide 2

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Endotherms such as
Energy conservation
mammals, expend a lot of
energy maintaining a
constant body temperature
· Problematic for small
animals with high
metabolic rates
· Sleep provides a period of
· WEBB 1982- described this
as the hibernation theory
of sleep…read more

Slide 3

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Time spent sleeping may be
constrained by food
Foraging requirements requirements
· Herbivores- eat plants- which
are relatively poor in
· More time spent eating- less
time available for sleep
· Carnivores-eat meat- high in
· Don't need to eat constantly-
more time for sleep
· Can conserve energy…read more

Slide 4

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Sleep constrained by risk of
Predator avoidance
· If an animal is a predator it
can sleep for longer
· Prey species' sleep time
reduced because animal
must remain vigilant to
avoid predators
· logically, to be safe the
animal shouldn't sleep at
all but sleep has a vital
function…read more

Slide 5

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MEDDIS 1975- sleep helps animals stay out
of the way of predators during parts of the
Hiding from predators day when they are most vunerable,
(waste of time) normally in hours of darkness, where they
will be hidden. Sleep may ensure the
animals stay still when they have nothing
better to do with the time
· SIEGEL (in YOUND 2008)- concurs with this
view and claims that being awake is more
dangerous than sleeping because an animal
is more likely to be injured
· Only possible explanation that for sleep that
allows energy conservation and keeping the
individual out of danger
· YOUNG 2008- the best strategy for passing
on our genes is to be asleep for as long as
· Little brown bat ­ awake for a few hours
each day, when insects it feeds on are
awake, because this animal is small it would
be expected that it would only spend little
time asleep…read more


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