Babies
sleep a lot, don’t they? That seems to be true for more than just
humans and mammals! A team of researchers from the Max Planck Institute
for Ornithology and the University of Lausanne uncovered fascinating new
information about REM sleep.
REM sleep (Rapid Eye Movement
Sleep) is the phase of sleep during which we experience our most vivid
dreams. During REM sleep, our brain experiences awa
ke-like
activity. A distinctive feature of REM sleep is that mammals earlier in
their lives experience a greater amount of REM sleep than adults. For
newborn humans, 50% of their sleep is REM sleep. Adults spend a quarter
or less of their sleeping hours in REM. Birds are the only non-mammalian
group of animals that are known to experience REM sleep. However, it
was unknown if baby birds experience more REM sleep than adults.
The researchers attempted to solve this mystery, using wild barn owls
as their subjects. Using minimally invasive EEGs and movement data
loggers, the scientists recorded the sleep behaviour in 66 owlets of
varying maturity. Throughout the recordings, which lasted for up to five
days, the owlets stayed in their nest and were fed normally by their
parents. After the recordings, all the owlets eventually fledged and
went on the breed in the following year. So it is clear that this
observational study had no adverse effects on the owls.
The
results showed that the owlets spent a large amount of time in REM
sleep, during which their brains showed awake-like activity. Although
their eyes remained closed, the owlets would slowly nod their heads. The
researchers also found that the time spent in REM sleep decreased as
the owlets matured.
The researchers also investigated the
connection between sleep and the expression of a gene responsible for
producing dark feather spots. The same gene is also necessary for the
production of thyroid and insulin hormones. These in turn are linked to
brain development in the owls. One of the researchers mentioned that
they had “found that melanic spotting in owls covaries with a variety of
behavioral and physiological traits, many of which also have links to
sleep, such as immune system function and energy regulation." They
discovered that owlets with a higher level of expression of the
abovementioned gene experienced less REM sleep than was expected for
their age. This suggests that they were experiencing greater brain
development than owlets with lower gene expression.
To
completely uncover the intricate relationships between REM sleep,
feather pigmentation and brain development, additional research must be
done. It is hoped that studying the variation of REM sleep with age can
provide a clue to the long-standing mystery of REM sleep.
Read all about it: http://bit.ly/145a2m1
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