Software Applications
These applications provide analysis and reporting of physiological signals
collected during sleep. Overnight oximetry enables screening and monitoring
of oxygen desaturation events associated with sleep-disordered breathing,
while overnight CO₂ monitoring is essential for the evaluation of
hypoventilation syndromes. Both complement full polysomnography by
providing objective, quantifiable respiratory data.
Sleep Apnoea and Related Breathing Disorders
This group encompasses disorders characterised by abnormal respiration during sleep. Sleep Apnoea subtypes (obstructive, central, mixed, and complex) are defined by distinct pathophysiological mechanisms but share common features of recurrent apnoea/hypopnoea events, oxygen desaturation, and sleep fragmentation. Related conditions – including snoring, upper airway resistance syndrome, nocturnal hypoxaemia, sleep-related hypoventilation, and obesity hypoventilation syndrome – may present independently or in conjunction with apnoea. Accurate characterisation using PG, PSG, oximetry, and CO₂ monitoring is critical, as diagnostic differentiation determines therapeutic approach.
Sleep-Related Movement Disorders
This category includes conditions associated with repetitive or sustained
muscle activity during sleep. Periodic limb movements, restless legs
syndrome, and sleep bruxism are identified by characteristic EMG activity
and may contribute to arousals, sleep fragmentation, and daytime
impairment. Diagnosis relies on PSG with targeted EMG channels to
differentiate pathological movements from benign variants.
Central Disorders of Hypersomnolence
These disorders are characterised by excessive daytime sleepiness not
explained by disturbed nocturnal sleep or misaligned circadian rhythm. They
include narcolepsy, idiopathic hypersomnia, and related presentations. The
Multiple Sleep Latency Test (MSLT) and Maintenance of Wakefulness Test
(MWT), performed following PSG, are gold-standard tools to quantify sleep
latency and assess for pathological REM sleep onset. Precise testing
protocols are essential for differential diagnosis and management.
Parasomnias
Parasomnias are undesirable physical events or behaviours arising during
sleep, typically from REM or NREM stages. REM sleep behaviour disorder
involves loss of REM atonia and dream enactment, while nocturnal epilepsy
produces stereotyped seizure activity that can mimic parasomnias. Video-EEG
PSG is the reference standard for capturing and differentiating these
conditions, with significant implications for safety and neurological
assessment.
Insomnia & Circadian Rhythm Disorders
These disorders involve difficulty initiating or maintaining sleep, or
misalignment between the endogenous circadian system and environmental or
social demands. Chronic insomnia is primarily a clinical diagnosis, but PSG
may be used to exclude comorbid sleep pathology. Circadian rhythm sleep-
wake disorders, including delayed sleep phase and shift-work disorder, are
evaluated using actigraphy, sleep diaries, and in some cases PSG, to
confirm phase shifts or rule out overlapping sleep disorders.