This chapter discusses sleep apnoea syndrome and snoring, where snoring is a noisy breathing of a person during sleep which disturbs the other persons around him. Snoring occurs due to airway obstruction during sleep in inspiration causing vibration of soft tissues of oropharynx. Sleep apnoea syndrome (SAS) is characterised by 30 apnoeic episodes each lasting for 10 sec or more in a sleep of about 6-7 hours. Important causes of SAS may be upper airway obstruction, obesity, alcoholism, hypertension, and drugs. Nocturnal polysomnography investigation includes ENG, EEG, ECG and pulse oximetry to see oxygen saturation levels. Muller’s sign is a reverse Valsalva’s sign where the patient pinches his nose and performs swallowing movements, where movements of the uvula are noted with endoscope. Respiratory disturbance index (RDI) in obstructive sleep apnoea (OSA) is the sum of number of apnoeas and hypoapnoeas number per hour.