and dolphins are
Dolphin’s brains, like ours, are divided into two hemispheres.
While one brain hemisphere sleeps the other
maintains breathing duties, motor behaviors and
possibly also some vigilance against predators.
different than us.
When dolphins are in sleep mode
they often lay motionlessly at the water surface or at the bottom of
a pool, or they might swim slowly, sometimes with one eye closed,
surfacing from time to time to breathe.
Dolphins appear to sleep or
rest many times throughout
the day and night.
theorize that some animals have developed this ability to help them detect
approaching predators or to periodically rise to the surface to breathe and
monitor wave patterns, which keeps them from drowning.
dolphins seemingly enter a fully asleep
state where both eyes are closed.
In this case
respiration is automatic; a tail kick reﬂex keeps
the blowhole above the water if necessary.
initially show a tail kick reﬂex
but it is not known if dolphins in the wild
reach this state.
Extensive research found new facts about how the brain of bottlenose dolphins works.
Scientists in California and Russia have discovered that dolphins,
including the killer whale mothers and calves do not sleep during the
ﬁrst few months of the new baby's life.
a neurobiology researcher,
says the sleep patterns he and his colleagues observed in the babies are "just
the reverse" of all other mammals, which normally sleep the most after birth
and gradually taper down to adult levels as they age.
"This is a challenge for the idea that sleep is necessary for
brain and body growth".
The Bottlenose Dolphin- by Stephen Leatherwood, Randall R. Reeve
The Dolphin in the Mirror: Exploring Dolphin Minds and Saving Dolphin Lives - By Diana Reiss.
Baby Dolphins Don't Sleep. UCLA Brain Research Institute. October 22, 2012.
American Psychological Association. Monitoring animal sleep.