Page 60 - IDF Journal 2023

IDF – Webinar Series IDF News – Spring 2023
An Introduction to the Classification of Sleep Disorders
Dr Peter Venn
Human beings sleep for approximately one third of their lives. Although sleep
is now understood to be
an important part of overall health, it still gets virtually no educational time in British medical schools, and at postgraduate level there is no GMC training programme leading to either a Certificate of Completion of Training (CCT) or a credential. Physicians with an interest
in sleep therefore come from a parent specialty, most commonly chest medicine, neurology, anaesthetics, ENT surgery or psychiatry.
Sleep is mentioned in ancient texts
by philosophers such as Aristotle and Galen, and in the Middle Ages be René Decartes, but during the 19th and 20th centuries scientific research into sleep rapidly developed, with the advent of the ability to measure physiological changes, together with their attendant consequences, during periods of sleep.
Sleep disorders are classified into six categories according to the International Classification of Sleep Disorders 3rd Revision – ICSD-3 (2013). The main categories and the disorders in each are listed in Table 1.
Physiological measurements during sleep, using polysomnography which includes electroencephalography with cardiorespiratory monitoring, has enabled us to get a profound understanding of the structure and neurophysiology of sleep. We now understand the pathways in the brain involved in maintaining wakefulness
and inducing sleep, both non-rapid eye movement (non-REM) and REM states, and the main nuclei concerned. These include the suprachiasmatic nucleus, which acts as the overall regulator of sleep, as well as nuclei in the brain stem and prefrontal cortex. The hypothalamus is the main area concerned with maintaining wakefulness and sleep.
A number of simple screening questionnaires including the STOPBang and Epworth Sleepiness Score enable physicians to quickly assess patients
with symptoms of sleep disorders, whilst physiological screening using simple devices, such as oximetry, have enabled an analysis of cardiorespiratory function during sleep in the home environment. Sleep disordered breathing (SDB), an umbrella term which includes various types of sleep apnoea, is now known to affect around 7% of the adult population in the western world rise. It rises with age to figures as high as 30% in demographic literature. The association of this condition with cardiorespiratory disease including myocardial dysfunction and heart failure makes it an extremely important area of concern in modern medicine.
A brief summary of the main conditions follows:
Insomnias
The insomnias are a group of disorders
in which there is difficulty initiating or maintaining sleep on at least 3 nights per week for 3 months. It may be acute when precipitated by external factors including the environment and stress, or chronic when it matures to be a psychological focus on sleep itself with a perpetuation of the problem. The Spielman model of “3 Ps” is a useful clinical model for chronic insomnia. Spielman postulated that
there were predisposing factors, often related to personality, and precipitating or trigger factors, leading to perpetuating or recurring factors. Chronic insomnia is common and, whilst traditionally treated with sleeping tablets in primary care, is much better approached using cognitive behavioural therapy. It is not uncommon to find underlying factors such as post- traumatic stress in patients with chronic
insomnia which require treatment also. An important aspect of insomnia is that
it must affect daytime performance.
If daytime performance is completely normal with no excessive sleepiness, the patient can be labelled as a short sleeper which many find difficult to accept, but does not require medical intervention.
Breathing related sleep disorders
Obstructive sleep apnoea (OSA)
is the term most general clinicians
are familiar with when talking about breathing problems in sleep. However, this is a specific diagnosis and a better terminology is the overarching term “sleep disordered breathing”. Whilst not
a final diagnosis, it indicates that there is a problem with breathing during sleep, which may be obstruction of the airway to a lesser or greater degree, central sleep apnoea, or Cheyne-Stokes respiration, which tends to be more related to cardiological malfunction.
Over the years, many treatments have been designed to improve obstruction to the airway, but continuous positive airway pressure (CPAP) remains the gold standard. This is closely followed by mandibular advancement devices which
We now understand the pathways in the brain involved in maintaining wakefulness and inducing sleep, both non-rapid eye movement (non-REM) and REM states, and the main nuclei concerned.
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