Knowledge guides

LG 12: Scientific foundations of sleep medicine (including investigations and measurements)

Epidemiology, pathophysiology, and clinical sciences

Advanced Trainees will have in-depth knowledge of the topics listed under each clinical sciences heading.

For the statistical and epidemiological concepts listed, trainees should be able to describe the underlying rationale, the indications for using one test or method over another, and the calculations required to generate descriptive statistics.

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Investigations, procedures, and clinical assessment tools

Advanced Trainees will know the scientific foundation of each investigation and procedure, including relevant anatomy and physiology. They will be able to interpret the reported results of each investigation or procedure.

Advanced Trainees will know how to explain the investigation or procedure to patients, families, and carers, and be able to explain procedural risk and obtain informed consent where applicable.

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Important specific issues

Advanced Trainees will identify important specialty-specific issues and the impact of these on diagnosis, management, and outcomes.

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Pathophysiology of normal and abnormal sleep
Anatomy and physiology of upper airway
  • concept of the pharyngeal airway as a collapsible tube
  • dynamic behaviour of the pharynx during breathing, when awake and asleep, and the concept of critical pressure
  • effects of craniofacial structure, obesity, upper airway muscle function, and ventilatory control on upper airway patency
  • effects of nasal resistance on pharyngeal collapsibility
  • role of upper airway muscles in the control of breathing when asleep and awake
  • structure and function of the upper airway
Physiology of sleep and breathing
  • breathing changes during sleep – REM versus NREM sleep
  • control of breathing during sleep
    • central and peripheral chemoreceptors, and hypoxic and hypercapnic ventilatory responses
    • central pattern generator as the basis for respiratory control
    • effect of sleep on respiratory neurons
    • neuroanatomical and neurophysiologic basis of control of breathing
    • peripheral and central afferents and inputs
  • effect of sleep on breathing in respiratory and neuromuscular diseases
  • explain the mechanics of breathing in an adult
Recommended sleep duration for adults, and consequences of sleep loss on physical and mental health and daytime functioning
  • circulating hormones and inflammatory cytokines impact on sleep-wake patterns, and influence of pregnancy and menopause on sleep
  • impact of circadian and homeostatic systems on sleep-wake cycles, and propensity to daytime sleepiness
  • influence of NREM and REM sleep and sleep arousal on respiratory, cardiovascular, endocrine, and gastrointestinal physiology
  • influence of NREM and REM sleep and sleep arousal on the autonomic nervous system
  • interactions between sleep and wakefulness and the sensory nervous system, perception and cognition, the cardiovascular system, temperature regulation, and the endocrine system
  • psychophysiology of the drowsy state
Sleep and circadian neurophysiology
  • anatomy and physiology of the circadian system
  • circadian, ultradian, and homeostatic processes that underpin sleep
  • cultural, social, and physical environmental factors impact on sleep
  • distinctions between REM and NREM
  • molecular and neural basis of the circadian system
  • neuroanatomical and neurophysiological basis for arousal from sleep
  • neuroanatomical, neurobiological, and neurophysiological basis for sleep and wakefulness, and for REM versus NREM sleep
  • normal sleep architecture, including the current classification of normal arousal patterns, normal sleep movements, and sleep stages
  • ontogeny of sleep and of breathing irregularities in sleep
  • sleep stages
  • sleep structure and sleep architecture changes with age
Assessment tools
  • Actigraphy
  • Computerised polysomnography (PSG) systems
  • Hardware and software of the computerised equipment used in a sleep service
  • Scoring of:
    • arousals
    • cardiac events
    • movements
    • respiratory events
    • sleep
  • Sensor devices used to measure physiological variables as part of sleep studies
  • Sleep diaries
  • Sleep monitoring equipment
  • Wearables and new technology
Procedures
  • Application of chin strap
  • Mask fitting and troubleshooting for positive airway pressure (PAP) therapy
  • Type 2 study set up
Sleep measurement and investigations
  • Brain CT
  • Cephalometry
  • Chest x-ray
  • Completing sleep investigation reports for different types of sleep studies
  • Diaphragm testing, such as:
    • maximal expiratory pressures (MEP)
    • maximal inspiratory pressures (MIP)
    • sniff nasal inspiratory pressure (SNIP)
  • Diaphragmatic electromyography monitoring
  • Indications for repeat investigations
  • Indications for sleep investigations:
    • awareness of the key professional documents outlining the performance of sleep investigations in Australia and Aotearoa New Zealand
    • circumstances when sleep investigations are not indicated
    • clinical features, mechanisms, and specific measurements of common sleep disorders
    • common questionnaire measurements of sleepiness and quality of life scores, and know the limitations of these measurements
    • definition of level 1 to 4 sleep studies and devices, the strength and weaknesses of each, and the role of in-laboratory versus ambulatory testing
    • effects of medications, comorbidities (such as psychiatric and medical conditions), and lifestyle on sleep wake patterns, and how these factors can affect measurements of sleep propensity
    • indications and use of tests for sleep propensity / vigilance
    • indications for investigation with level 1 to 4 sleep studies
    • wearable devices and new technology for measuring sleep and sleep disorders, and their strengths and limitations
    • what measurements are possible and appropriate for disorders listed in the International Classification of Sleep Disorders (ICSD-3)
  • Limited channel sleep studies, including normal and abnormal patterns and interpretation of raw data, and the ability to discuss the strengths and limitations of:
    • cardio-respiratory sleep studies
    • limited channel PSG studies
    • overnight oximetry
  • Methods of measuring respiration during sleep
  • MRI scan
  • Oesophageal pressure monitoring
  • Positive airway pressure titration and review studies – continuous positive airway pressure (CPAP) and bilevel non-invasive ventilation
  • Principles of measurement parameters:
    • measurements across the range of sleep studies, and determine adequacy of recording techniques
    • measurements indicated for further evaluation in the event of a non-diagnostic sleep study
  • PSG recording:
    • age-appropriate normal sleep stage distribution and proportions
    • arousals
    • period limb movement (PLM), PLM-I
    • raw data from sleep studies, including:
      • airflow parameters
      • airway pressures
      • body position
      • chin electromyography
      • EEG
      • effort parameters
      • electrocardiography (ECG)
      • electro-oculogram (EOG)
      • leg electromyography derivations
      • measures of CO2
      • oxygen saturation
      • video recordings
    • REM sleep without atonia (RSWA)
    • respiratory events:
      • apnoeas – central, mixed, and obstructive
      • hypopnoeas
      • respiratory effort-related arousals
    • scoring criteria, and recognising how different scoring criteria may alter results and therefore interpretation of severity
  • Questionnaire measurements for sleepiness and sleep disorders
  • Respiratory function tests to assess sleep breathing disorders:
    • arterial blood gases (role of capillary and venous blood gas measurements)
    • gas transfer
    • lung volumes
    • oximetry
    • spirometry
    • tests of respiratory muscle strength
  • Sensitivity of the different measurements of respiration
  • Sleep propensity tests:
    • multiple sleep latency test (MSLT)
    • maintenance of wakefulness test (MWT)
  • Educate patients, their families, health professionals and the public about the nature and importance of normal sleep, and the detrimental effects of sleep loss
  • Infection control and prevention of cross-infection
  • Influence of other disease processes on common measurement parameters:
    • cardiovascular disease (e.g. heart failure)
    • chronic obstructive pulmonary disease (COPD)
    • obesity
    • respiratory muscle weakness
    • stroke
  • Limitations and common parameters in sleep investigation