Dr Marcus Sim Jin Hui is an Associate Consultant in the Department of Respiratory and Critical Care Medicine at Changi General Hospital, with a concurrent appointment at the SingHealth Duke-NUS Sleep Centre. He obtained his MBBS in Australia and holds MRCP (UK) and a Master of Medicine in Internal Medicine.
His clinical interests include obstructive sleep apnoea, obesity hypoventilation syndrome and chronic non-invasive ventilation for patients with chronic respiratory failure, alongside general respiratory conditions such as asthma, COPD, bronchiectasis and interstitial lung disease.
He holds teaching roles within SingHealth and at the Lee Kong Chian School of Medicine, NTU.
Clinical focus
Sleep medicine (OSA).
Qualifications (as publicly listed)
MBBS, MRCP (UK), M Med (Internal Medicine).
Where they practise
- Clinic / practice: Department of Respiratory & Critical Care Medicine, Changi General Hospital — Simei
- Hospital / training affiliation(s): Changi General Hospital; SingHealth Duke-NUS Sleep Centre
Getting to the clinic
The Department of Respiratory and Critical Care Medicine is based at Changi General Hospital (CGH) in the east of Singapore, and Dr Sim also holds an appointment with the SingHealth Duke-NUS Sleep Centre. The hospital is served by nearby MRT and bus routes; Expo MRT on the East-West and Downtown Lines is close, with a short bus or taxi connection to the hospital, and the Simei area is nearby. Taxi and ride-hailing drop-off is available at the main entrance, and as a public hospital CGH has visitor carparks on site for those driving.
On a first visit, check your appointment letter for the specific clinic location and use the hospital’s signage and information counters to find your way. If a sleep study is arranged, the location and timing will be explained separately. Arriving early helps with registration.
What sleep medicine and OSA care covers
Dr Sim’s clinical interests include obstructive sleep apnoea (OSA), obesity hypoventilation syndrome and chronic non-invasive ventilation for patients with chronic respiratory failure, alongside general respiratory conditions such as asthma, COPD, bronchiectasis and interstitial lung disease. Obstructive sleep apnoea is a condition in which the upper airway repeatedly narrows or closes during sleep, interrupting breathing. This can cause loud snoring, pauses in breathing noticed by a bed partner, choking or gasping, restless sleep and daytime sleepiness, and over time is linked with high blood pressure and other health risks.
Obesity hypoventilation syndrome and chronic respiratory failure involve under-breathing, where the body does not clear enough carbon dioxide, sometimes needing non-invasive ventilation support at night. Assessment and treatment of these conditions aim to improve sleep and breathing, reduce daytime symptoms and lower associated health risks. Treatment for OSA often includes weight and lifestyle measures and devices such as continuous positive airway pressure (CPAP).
What to expect at a consultation
A first consultation usually begins with a history of your sleep and breathing, including snoring, witnessed pauses, daytime sleepiness, and any related conditions such as high blood pressure. The doctor may use questionnaires to assess sleepiness and examine your airway, neck and chest. To diagnose sleep apnoea, a sleep study (polysomnography or a home sleep test) is often arranged to measure your breathing and oxygen levels overnight.
The results are discussed with you, along with a treatment plan. For OSA this may include CPAP therapy, weight management and lifestyle changes, and sometimes other devices or referrals. For under-breathing conditions, non-invasive ventilation may be considered. You are encouraged to ask about using a CPAP machine and what to expect.
Preparing for your appointment
It helps to bring:
- Your photo identification and a GP or polyclinic referral letter, which can help with subsidies.
- Previous records, any past sleep study results, and chest imaging.
- A current list of all medicines and supplements.
- A sleep diary or notes on your snoring, daytime sleepiness and any pauses your partner has noticed.
- A written list of questions, and details of any current CPAP or sleep device.
After your consultation and follow-up
Sleep and breathing conditions are usually managed over time. After your visit you may have a sleep study arranged, then follow-up to review the results and start or adjust treatment such as CPAP. Ongoing review checks how well therapy is working and helps with any difficulties using a device. Referrals to other services, such as weight management or ear, nose and throat, may be made where helpful. Reports and results can be obtained through the hospital. A second opinion is your right. Seek urgent care for severe breathlessness, chest pain or marked confusion or drowsiness.
Booking, referrals and fees
As CGH is a public hospital, a referral from a GP, polyclinic or another doctor is generally the usual route and can support subsidy eligibility for citizens and permanent residents. For eligible procedures, devices and admissions, MediSave, MediShield Life and Integrated Shield Plans may apply within set limits, while outpatient consultations are commonly paid out of pocket. Subsidy and billing depend on your status and services used, so confirm current fees directly with the hospital.
Common questions
What is obstructive sleep apnoea?
It is a condition in which the airway repeatedly narrows or closes during sleep, interrupting breathing. It often causes snoring, poor sleep and daytime tiredness, and can affect long-term health.
How is sleep apnoea diagnosed?
Usually with a sleep study, either overnight in a sleep laboratory or with a home test, which measures your breathing and oxygen levels while you sleep.
What is CPAP and do I have to use it forever?
CPAP is a device that gently keeps the airway open during sleep. Many people use it long term, as it works while it is being used; your doctor reviews how it is helping and addresses any difficulties.
Can weight loss help sleep apnoea?
For many people, yes. Weight and lifestyle measures can reduce the severity of OSA and are often part of the overall plan alongside other treatments.
Related guides
Sources & verification
See also: our editorial directory of respiratory physicians (lung specialists) in Singapore and our shortlist of respiratory clinics.
This is an independent, factual profile compiled from the public sources listed above — not a paid listing, advertisement or endorsement. Details can change; always verify a doctor’s current registration on the Singapore Medical Council public register and confirm specifics directly with the clinic. This page is general information, not medical advice or a recommendation of any individual practitioner. See our editorial policy.
Don’t agree with this listing? If this is your profile and you’d like the details corrected, updated or removed — or you’d like to be featured — please reach out to us or use our contact form. We’ll sort it out quickly.