Overnight rostral fluid shift is one of the contributing factors for worsening obstructive sleep apnoea (OSA). Fluid shift has been recognized to play a role in the pathophysiology of sleep apnoea. Previous studies shown that fluid from the leg redistributes to the neck at night increases the neck circumference, hence indicating fluid accumulation in the neck. OSA patients are more susceptible to developing upper airway narrowing in response to fluid shift from the leg to the head and neck region.

Previous studies were mainly done on Caucasian patients. The pathophysiology of OSA in Caucasian patients and Asian patients are different but both suffer a similar degree of OSA. The investigators would like to investigate if reducing leg swelling by a simple non-invasive intervention of wearing compression stocking during the day can attenuate sleep apnoea, and whether compression stocking is generally acceptable and well-tolerated among the general OSA population in Asia.

Inclusion Criteria:

• Aged 30 years old to 65 years old.
• Either STOP-Bang score of ≥3 or Epworth sleepiness scale indicating mild excessive daytime sleepiness to severe excessive daytime sleepiness (11-24 points).
• Has pre-existing diabetes mellitus and/or hypertension and is on medication.
• Ability to provide informed consent.
• Not working night shift.

Exclusion Criteria:

• Significant arterial disease due to the risk of limb ischaemia and necrosis.
• Not pregnant and not planning to get pregnant before the end of the study.
• History of psychiatric disease.
• Patient who are on wheelchair.
• Patient who has cardiac failure and or stroke.
• Patient who has end-stage renal failure. Estimated glomerular filtration rate <15ml/min/1.73m2 or on renal replacement therapy i.e. dialysis or renal transplant.
• Patient who has liver disease.
• Patient who are on pacemaker, and metal implants.
• Patient who are on CPAP treatment for OSA.
• Patient who are illiterate.
• Medications which affect fluid balance or level of consciousness (e.g. diuretics, non- steroidal anti-inflammatory drugs (NSAIDS), corticosteroids, sedatives, opiates) at any time during the study.