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.
