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Sleep
Why we grind our teeth at night
The mind never sleeps. All night long it triggers a deglutition
reflex. But in some people, the reflex is preceded by a
noisy grinding of the teeth, which can take place up to
15 times an hour! Bruxism affects 8% of people aged 11
to 59 years. This repeated grinding causes the teeth to
deteriorate, along with jaw pains and headaches—not to
mention the discomfort this means for a bedpartner.
We used to believe that children who grinded their teeth
at night had worms. Medicine has proven this belief wrong,
and explained bruxism, or clenching, as a result of poor
contact between teeth. This involuntary habit was then
associated with stress and anxiety. Gilles Lavigne, a researcher
in the Faculties of Dentistry and Medicine at Université de
Montréal, explains that “the development of neurobiology
has enabled us to better understand the structure of sleep
in clenchers and to define bruxism clearly as one of many
cyclic phenomena that are characteristic of sleep.” The
researcher and his team at Sacré-Cœur hospital in
Montréal have now gained international recognition
for establishing criteria to identify nocturnal bruxism.
“In the brain there is a region called the movement generating
centre, which synchronizes several rhythmic activities,
such as walking, heartbeat, respiration, chewing, deglutition,
etc. In a person suffering from bruxism, the centre seems
to send unsynchronized signals to the jaws, which causes
clenching of the teeth. It is as if the mind was activating
the centre, but without any apparent reason,” explains
Mr. Lavigne, whose chief interest is primary bruxism, where
the subject does not suffer from neurological diseases
or disorders and is not on medication.
Does the generating centre trigger an excessive response
when the mouth and esophagus are not sufficiently lubricated,
or when the respiratory tract is partially obstructed?
This is the type of question the researcher and his team
are now asking. And this line of questioning could lead
to the development of drugs to aid secondary clenchers,
whose sleep is disrupted by involuntary movements or spasms
of the face, neck and members.
In reply to a frequent question about the complexities
in studying sleep, Gilles Lavigne notes that “bruxism is
complex to study. First of all, you have to find good subjects,
which is not easy, especially when they have to be available
to spend a few nights in the laboratory. It is also a very
long process, because you must then get the subjects accustomed
to sleeping under video surveillance, connected to polygraphs
by a mess of wires. Lastly, a night of recording takes
from four to seven days to analyze.”
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