Sleep disorders
Dr Alison Bentley
School of Physiology, Wits
University
Have you ever woken at night to find yourself unable to move at all?
Have you fallen asleep while driving?
Do you work shifts and find yourself unable to get a normal sleep
pattern going?
These and many other unusual happenings all fall in the domain of the sleep
researcher. While the concept of watching someone sleep may not be your cup of
tea, there are many researchers and medical personnel around the world who do
just that.
Sleep research falls into 2 very distinct fields - the pure science and the
sleep disorder field.
Many scientists are still looking to solve some fundamental issues about
sleeping - such as why do we sleep? (Apart from just making sure we don't fall
asleep the next day!)
Sleep Paralysis
Research in this area ranges from investigating the basic neurological
mechanisms such as the paralysis that occurs during REM or dreaming sleep. The
importance of the paralysis may be to prevent us acting out our dreams and
certainly creates the feeling of an inability to move or run away when we are
faced by nightmares. If this paralysis doesn't stop on waking, people may
experience sleep paralysis and an inability to move when they wake up as in the
scenario described above.
In elderly men, particularly, the normal paralysis during REM sleep may not
occur due to aging changes. They then get up during a dream and act it out.
Depending on the content of the dreams they may run out of the room fighting off
tigers, play soccer or just walk through the imaginary landscape their memory
banks are creating.
24-hour body Rhythms
Other research looks at our circadian rhythms - from circa (about) and dian
(a day). These are our 24-hour body rhythms including changes in body
temperature, plasma levels of various hormones and variables such as heart rate
and blood pressure. These and many other variables increase and decrease at
various times during the day and night and determine when we need to sleep and
be most alert. Simply changing our desired bedtime such as during shift work or
when traveling across time zones does not guarantee that our body will be ready
to sleep when we want it to. All the other rhythms need to be changed as well
and that can take up to 7 days to occur. However, shift work is a reality as we
all like buying petrol during the night and want doctors to be available when we
have an emergency. So we need to find the best ways for these workers to handle
the problems of shift work.
We all know that if we are sick or sore that our sleep tends to be
interrupted. The scientific literature however, cannot tell you at present how
much pain will interrupt your sleep, how it will change the character of your
sleep and what medication is the best to resolve that problem. So researchers
spend nights letting people fall asleep and then hurting them slightly to see
what the impact on their sleep is. A job for the more masochistic!
The other large field of sleep research is that focusing on clinical sleep
disorders. These fall into 3 main groups: insomnia, hypersomnia and parasomnia.
Insomnia
The insomniac is unable to get sufficient sleep for their daily needs. While
this can be caused by the circadian problems mentioned above there are many
other causes. Some of these causes are environmental such as excessive noise
while at other times a secondary medical problem may result in a sleep problem.
This may occur either due to the problem itself such as with chronic pain or the
medication used to treat the disorder itself causes a sleep problem such as the
lipid lowering medications.
Psychological causes form a large percentage of the cases of insomnia.
Patients describe it as a bad habit where they go to sleep and find themselves
becoming so anxious about not being able to sleep that they don't. It can take a
long time to teach them to trust their own abilities ad research continues into
the best way to do that so that they don't relapse.
Some patients can't sleep because they have restless legs syndrome. This can
be a very frustrating condition which occurs mainly at night when the sufferer
sits and relaxes after a hard day. They get a strange uncomfortable, stretching,
pulling feeling in their calf muscles. So uncomfortable that they cannot sit
still and have to walk around for a few minutes Then it feels better so they sit
down again - only to find it comes back after 10-15 minutes. We don't know what
causes it - hence the research, but we're beginning to get a handle on how to
medicate these patients so that the feeling goes away.
Research in this area therefore needs to look at what areas of the brain or
spinal cord are actually inducing these sensations, who is most likely to get
them and what can we do about them.
Hypersomnia
Hypersomniacs occur when people have a good night's sleep in terms of hours
spent sleeping but then find that they feel sleepy during the day. This
sleepiness can become so severe that they fall asleep while at work or
particularly dangerously when they are driving their car. The daytime sleepiness
has a particularly severe impact when the sufferer is driving a bus, airplane or
train, which is transporting other people. The two major disorders that fall
into this area are narcolepsy and obstructive sleep apnea.
Narcolepsy is a disorder of REM sleep and present with isolated features of
REM sleep including the paralysis as well as the dreams
themselves mentioned above. Normally these features
"switch" off as soon as we wake up. In narcolepsy, REM sleep intrudes
into the sufferers' daily lives, meaning that they can fall asleep at a moments notice or
have a dream like experience before going to sleep at night. They also suffer
from the sleep paralysis mentioned above as well as paralysis during the day if
they suddenly laugh or get angry. All problems which can cause an enormous
amount of distress. Studies into the mechanism of this disease are moving into
the field of molecular genetics and the discovery of a gene that may be
involved.
Obstructive sleep apnea is a fairly common sleep disorder and comprises the
major group of patients being admitted to the diagnostic sleep laboratories.
These laboratories monitor the patient overnight, report on the abnormalities
and then ensure that treatment is arranged if necessary. You can detect a sleep
apneac by their really bad snoring - not only do they make a large amount of
noise, but they stop breathing, gasp and then start snoring gain. Although this
particular disorder is the butt of many jokes the person suffering from it can
be severely affected by the whole process. Every time they stop breathing their
airway has closed down. This means that they cannot breathe and their brain is
forced to wake them up to start breathing again and keep them alive. The
patients who have severe sleep apnea can stop breathing up to 600 times per
night meaning that they are also waking up that many times.
Waking up 600 times per night is guaranteed to make you feel tired and sleepy
the next day. If this carried on for weeks or months you can begin to understand
why they fall asleep during the day. Along with the sleepiness comes an increased
risk of getting hypertension, right-sided heart failure and possibly an increased
risk of strokes. So research continues into the mechanisms behind the apnea, who
is most likely to get it, how can we recognize them and how much of a medical
problem is it?
Parasomnia
The group of parasomnias covers all those disorders which don't usually
affect the quality of sleep but rather induce strange events during the night
such as sleepwalking, talking, night terrors and REM behavior disorder. All termed
disorders of arousal, usually inherited from family and not really causing any
major problems.
Research at Wits
Research into sleep disorders itself has been growing since the use of the
Electroencephalogram (EEG) in the 1950's. It's a relatively new field in
medicine but an exciting one. Wits University has the only
dedicated sleep research laboratory in South Africa. The various researchers have
many interests and the projects are a popular choice amongst the Honours
students in the school of Physiology.
We offer workshops in shift work to help employees cope with the demands
placed on them and have been active in helping spread information about sleep
research and sleep disorders through the Sleep Society of South Africa. This is
a non-profit organization comprised of medical doctors and researchers
interested in sleep.
Dr Alison Bentley BSc MBBCh Clinician and Lecturer Wits Sleep Laboratory
School of Physiology Faculty of Health Sciences Wits University
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