List of accesskeys skip navigation

Clinical Specialties & Centres

Skip Navigation LinksHome > Clinical Specialties & Centres > Respiratory and Critical Care Medicine > Sleep Disorders Unit

Sleep Disorders Unit

Block 5 Level 4

Outpatient Appointments
Tel : 6326 6621
Fax : 6321 4380

Sleep medicine is a relatively new medical field and the spectrum of sleep disorders is very wide. The diagnosis and management of various sleep conditions often involve many different medical and surgical disciplines, and it is our belief that this is best accomplished in an expert, multidisciplinary sleep center.
The Sleep Disorders Unit in SGH is the largest in Singapore with the most comprehensive range of inpatient and outpatient services for the evaluation, treatment and education of patients with sleep disorders. The range of sleep disorders managed here include obstructive sleep apnoea, sleep disordered breathing, snoring, obesity hypoventilation syndrome, chronic respiratory failure, parasomnias, nocturnal epilepsy, REM sleep disorders, leg movements disorders and insomnia. Our sleep specialists come from a multidisciplinary background with respiratory physicians, ENT surgeons, neurologist, psychiatrists and psychologists all working in a collaborative environment.

We offer outpatient consultation services and both portable home and inpatient sleep studies. These sleep studies include measurements of brain wave activity, respiratory breathing patterns and leg movements and inpatient studies are fully attended by sleep technologists. We are proud to be the only Australasian Sleep Association/National Association of Testing Authorities-accredited sleep service in Asia.

History of Sleep Disorders Unit in SGH

  • Clinical sleep medicine only started as a practice in the 1970s.
  • Dr K. Puvanendran, a Neurologist from SGH, pioneered Sleep Medicine in Singapore. He led a multidisciplinary team of doctors and sleep technologists and established Singapore's first dedicated sleep laboratory in Ward 48 in 1987, supported partly by generous donations from the Shaw Foundation.
  • Initial sleep studies were done using a SIEMENS 16 channel EEG machine with pen and paper.
  • More than 1000 paper pages had to be visually analyzed each night! Thankfully, digital recording overtook analog in the late 1980s.

Sleep Disorders

Types of Sleep Disorders (link available from SingHealth website conditions and treatment)

  1. Obstructive Sleep Apnea
  2. Sleep Disordered Breathing & Snoring
  3. Sleep Movement Disorders
  4. Sleepwalking
  5. Insomnia
  6. Sleep Deprivation

Types of treatment

  1. Surgical treatment for Snoring and OSA
  2. CPAP therapy
  3. OSA – Dental and Maxillo management
  4. Mandibular Advancement Splint (MAS)

Outpatient Services

  • Consultation clinics
    Our Sleep physicians from different disciplines conduct dedicated weekly clinics for the diagnosis, evaluation and management of various types of sleep disorders. Examples of sleep disorders by disciplines include:
  1. Respiratory Sleep: mainly Sleep-related breathing disorders (SRBD) which includes Obstructive sleep apnea, Obesity hypoventilation syndrome (OHS).
  2. Neurology Sleep: Sleep-related movement disorders which includes REM behaviour disorder (RBD), Periodic limb movement disorder (PLMD), Sleepwalking/ Sleep talking, Sleep terrors, Excessive daytime sleepiness (EDS), Narcolepsy, Circadian rhythms disorder.
  3. ENT Sleep (Ear nose throat): Excessive snoring, Sleep apnea.
  4. Psychiatry Sleep: Insomnia, Circadian rhythm disorders.
  • Positive Airway Pressure (PAP) therapy and services
    We offer education and counseling services to patients who are have been diagnosed with obstructive sleep apnea on the initiation and use of Positive Airway Pressure therapy.
  1. Education services include the various mask interfaces, types of PAP therapy, benefits of PAP therapy, costing and availability of PAP equipment.
  2. Acclimatization to PAP therapy and PAP troubleshooting techniques.
  3. Mask fitting techniques
  4. Education on use and care of PAP machines and accessories such as chinstraps & heated humidifiers.
  5. Sale of mask interfaces
  6. Rental for trial of PAP equipment
  7. Downloading and interpretation of compliance data from PAP devices.
  • Cognitive behavioral therapy (CBT)
    CBT is a type of counseling aimed at changing behavior. It is an effective tool to treat insomnia and other psychiatric conditions.

Inpatient Services – Types of sleep studies

  1. Overnight Diagnostic Polysomnography (PSG)  also known as an Inpatient Sleep Study
    This is the most common type of sleep study done to record and analyse your night time sleep patterns and to identify any underlying sleep disorder. “Poly” is greek for multiple, “somno” is greek for sleep and graphy refers to recordings. Sensors are attached by stickers, tape or belts and no needles are involved.

    Recordings captured during a sleep study may include:
    Electroencephalography (EEG) -  Measurement of brain wave activity which help to define one’s sleep stages.
    Electrooculogram (EOG) - Measurement of eye movements
    Electromyography - Measurement of muscle activity e.g leg movements, chin muscle activity.
    Electrocardiogram - Measurement of electrical heart activity and heart rate.
    Other recordings include: breathing patterns, oxygen saturation, snoring sounds and video monitoring.
  2. CPAP titration study
    For patients with OSA or other sleep related breathing disorders, Positive Airway Pressure therapy is sometimes required. Optimal pressure requirements are different for each patient and a CPAP titration study is one way to determine the optimal pressure requirement, to ensure the efficacy of PAP therapy and to manage any adverse effects that may arise. 
  3. BIPAP titration study
    This is another type of an in-lab positive airway pressure titration sleep study utilizing a different kind of ventilator – a bilevel ventilator. It is indicated when respiratory failure is more severe and CPAP therapy is insufficient.
  4. Multiple sleep latency test - MSLT
    MSLT is used to aid in the diagnosis of narcolepsy and idiopathic hypersomnia by measuring the severity of daytime sleepiness. It is full day test consisting of 5 scheduled 20-minute naps separated by a 2-hour breaks and is usually performed in the day following an overnight diagnostic PSG. For each nap, the patient is instructed to lay in bed in a dark quiet room and asked to try and fall asleep on command. Sensor and electrodes are used to record the time needed to fall asleep and the track the sleep pattern. If the time taken to fall asleep (sleep onset latency) is very short, it may indicate a pathological level of daytime sleepiness. You may bring along your own reading material to keep you occupied during the break intervals.
  5. Maintenance wakefulness test - MWT
    This is a full day test that measures your ability to remain awake during the day. It is indicated when there is a need to assess the objective response to treatment in patients with excessive daytime sleepiness e.g. in pilots or truck drivers with OSA. Test subjects are sat down in a dark quiet room and instructed to stay awake for 20 minutes at a time. Sensor and electrodes are used to record the time taken to fall asleep. This is repeated 4 times during the day and being able to resist any sleep is an indication of a satisfactory level of daytime alertness.
  6. Full EEG Sleep Study
    A Full EEG sleep study is indicated when sleep seizures are suspected. This is similar to a PSG except that more EEG electrodes are applied to capture more brain wave activity during the sleep study.
  7. Transcutaneous Carbon Dioxide monitoring
    Trancutaneous carbon dioxide monitoring is a non-invasive way of continuously measuring blood carbon dioxide levels during a sleep study using a heated electrode sensor applied to the skin with a sticker. It is usually performed in sleep disordered breathing patients e.g obesity hypoventilation syndrome, when nocturnal hypoventilation is suspected.


  1. Overnight pulse oximetry
    The overnight pulse oximetry device monitors and records the blood oxygen saturation levels throughout the night. It is usually performed to look for evidence of nocturnal OSA or hypoventilation or to confirm the efficacy of the prescribed positive airway pressure therapy. It can be done at home or as part of your stay in the hospital. It is a painless procedure using a very simple device, a probe-like sensor clipped onto a finger for continous monitoring overnight. A report showing the trending oxygen levels will be generated upon returning of device and will be given to the sleep physician for interpretation.
  2. Actigraphy monitoring
    Actigraphy is a test used to record and continuously monitor human rest/activity levels over an extended period of time via the Actiwatch. This is a lightweight medical device worn on the wrist like a watch. It records motion and light which can then be used to analyse sleep and wake cycles and help in the diagnosis of circadian rhythms disorders, irregular sleep wake patterns, advanced/delayed sleep phase syndrome or shift-work sleep disorders.
  3. Home based sleep study – WatcPat study
    The WatchPAT is a type of portable home sleep study device, which can help in the diagnosis of leep related breathing disorders. It records the peripheral arterial tonometry (PAT), oxygen saturation, actigraphy, snoring, and body position of the patient. WatchPAT provides a cheaper alternative to an inpatient  sleep study with the added benefit of being able to be performed in the comfort of the patient’s own bedroom. However, this device should only be used in patients with a higher likelihood of OSA and without any other complicating medical conditions, hence careful screening by a sleep physician beforehand is mandatory.

Last Modified Date :11 Feb 2018