A new study published in
Current Biology is
investigating why you get poor sleep in unfamiliar
places. It suggests that when people sleep in an
unfamiliar place, one hemisphere of the brain stays
more awake as a way to keep watch for potential
danger possibly a remnant of the days when
Homo
sapiens had to guard their territory every night.
This phenomenon is known as
unihemispheric slow-wave sleep, and it’s seen in
marine animals and some birds. This is the first
study to suggest that the human brain may also be
hard-wired to function in a similar way, although
on a smaller scale. Humans, unlike sparrows,
don’t usually sleep with one eye open. However,
when in new surroundings, one hemisphere of the
brain may stay at least a little bit awake – great for
waking quickly if an intruder shows up, but with a
resulting groggy feeling the next morning.
The group of researchers recruited sleep
study participants, and conducted neuroimaging
along with polysomnography, a standard test used
in sleep labs to monitor brain waves, oxygen level
in blood, heart rate, breathing, and eye and leg
movements. They discovered that only the brain’s
right hemisphere was consistently engaged in
slow-wave, or deep, sleep. The left hemisphere – the
side responsible for logical thinking and reasoning –
had what the researchers called “enhanced vigilance”,
which also made the entire brain more responsive
to sound.
The researchers tried a test where they
targeted sounds to the left and right ear. They found
that on the first night, 80 percent of the arousals
from deep sleep occurred when sound was made to
target the right ear (the brain’s left hemisphere). On
day two, that number dropped to about 50 percent.
FIRGER, Jessica. Disponível em: <http://www.newsweek.com/authors/ jessica-figer>. Acesso em: set. 2018. Adaptado.
