SLEEP PHYSIOLOGY
Sleep is a basic fundamental process that all humans need. The average human spends between 6 to 8 hours per day or about one third of their lifetime sleeping. Sleep is defined as reversible state of altered consciousness with perceptual disengagement from one’s environment.
The average Singaporean’s life expectancy is about 80 years old, hence, if we sleep one-third of our lives, we spend about 26 years of our life sleeping!
Contrary to popular belief, sleep is an active process involving complex interactions between the brain, subconscious centers and the rest of the body. Sleep has two main phases, the rapid eye movement (REM) phase, where dreams occur (dream sleep), and the non-rapid eye movement (NREM) phase.
Depending on the age and health of the individual, the percentage of each phase varies. The older the person, the lesser the proportion of REM sleep. In general, a healthy adult would spend about 15 to 20 per cent in REM sleep. An infant can spend up to 50 per cent in REM sleep.
Scientists believe that REM sleep is more important of the two phases. It is believed that REM sleep is essential for rejuvenation and well-being of the individual. They also have linked REM sleep to better memory function and cognitive ability.
Hence, any interruptions, disturbance or abnormalities during one’s sleep can have deleterious effects on one’s health. These disturbances of sleep can manifest at night and during the day.
SLEEP DISORDERS
Sleep disorders are a fairly common disease for humanity. They range from sleep walking, sleep paralysis, insomnia, narcolepsy to sleep apnoea. The commonest sleep disorder is obstructive sleep apnoea, and the commonest presenting symptom of sleep apnoea is snoring.
An American research study showed that in a 30 to 35-year-old population, 20 per cent of men and 5 per cent of women will snore, and by the age of 60, 60 per cent of men and 40 per cent of women will snore habitually.
Obstructive sleep apnea is a common sleep disorder and is estimated to have an incidence of 24 per cent in men and 9 per cent in women. Many authorities believe that up to 93 per cent of females and 82 per cent of males with moderate to severe OSA remain undiagnosed.
SNORING
Snoring is frequently deemed as a social nuisance. Not a nuisance to the snorer, but a nuisance to the bed-partner. Most patients who snore do not believe that there is anything wrong with them, until perhaps their spouses’ sleep quality has been adversely affected or they find that they are excessively tired, fatigued and are falling asleep behind the wheel.
The presence of snoring is an “alarm” that alerts one to the possibility of a sleep disorder. It is due to the vibration of the soft palate, uvula base of tongue and other soft tissues in the throat during inhalation.
Sleep-disordered breathing is a spectrum of diseases related to decreased airflow through the upper airway during sleep, due either to complete or partial upper airway obstruction.
These encompass:
simple snorers (patients who snore without excessive daytime tiredness), and
obstructive sleep apnoea (OSA), (patients who snore and have pauses in breathing during sleep, with both excessive daytime somnolence and an abnormal sleep study).
Symptoms of OSA include …
During the day:
- Daytime sleepiness, tiredness
- Poor concentration
- Poor memory
- Morning headaches
- Mood changes
- Irritability
During the night:
- Choking sensation at night
- Gasping for air at night
- Frequent arousals
- Nocturia (frequent passing urine)
- Loud snoring
These sleep disorders result in poor sleep quality, fragmented sleep, intermittent nocturnal hypoxia and nocturnal hypertension. OSA has been found to have profound effects on the cardio-respiratory systems. The Sleep Heart Health Study and the Wisconsin Sleep Cohort have demonstrated a strong link between OSA and hypertension. Patients with OSA have a 1.6 to 2.3 times higher chance of an acute myocardial infarct and stroke than a normal patient.
PATHOPHYSIOLOGY
The fundamental abnormality in sleep-disordered breathing is in the collapsibility of the anatomy in the upper airway.
It is a balance between the box (jaw) and the amount of soft tissues in the box (that is the palate, uvula, tonsils, tongue, side walls and soft tissue in the pral cavity). Hence, partial or complete upper airway obstruction during sleep can be due to excessive soft tissue content or an abnormally small facial skeletal framework (box).
Overweight patients have an exaggerated disease due to a crowded upper airway with very little space for airflow. When the bulk of this soft tissue exceeds a certain amount, it leads to collapse (partial or complete) of these structures, which then leads to upper airway obstruction during sleep.
With recurrent episodes of apnoea (stoppages in beathing), associated with hypoxaemia (low oxygen in the blood), there is increased strain on the heart and the brain, resulting in hypertension, ischaemic heart disease and strokes. Severity of OSA is measured in terms of the number of apnoeic (stoppages in breathing) episodes per hour over a night’s sleep.
DIAGNOSIS
Diagnosis of OSA requires a thorough clinical examination, and a flexible nasoendoscopy. A sleep test is required. The latest sleep test is an overnight home based wrist worn device with only two stickers/probes on the fingers of the patient (Figure). This sleep test is worn in the comfort of the patient’s own home. This sleep test has been found to be very accurate in diagnosis of snoring/obstructive sleep apnea.
Diseases associated with OSA:
- Obesity
- Hypertension
- Ischaemic Heart Disease
- Stroke (Cerebrovascular Accidents)
- Diabetes Mellitus
SLEEP HYGIENE
DO:
- Go to bed at the same time each day.
- Get up from bed at the same time each day.
- Get regular exercise each day, preferably in the morning. There is good evidence that regular exercise improves restful sleep. This includes stretching and aerobic exercise.
- Get regular exposure to outdoor or bright lights, especially in the late afternoon.
- Keep the temperature in your bedroom comfortable.
- Keep the bedroom quiet when sleeping.
- Keep the bedroom dark enough to facilitate sleep.
- Use your bed only for the two “S” – sleep and sex.
- Take medications as directed. Its is often helpful to take prescribed sleeping pills one hour before bedtime, so they are causing drowsiness when you lie down, or 10 hours before getting up, to avoid daytime drowsiness.
- Use a relaxation exercise just before going to sleep.
- Muscle relaxation, imagery, massage, warm bath, etc.
- Keep your feet and hands warm. Wear warm socks and/or mittens or gloves to bed.
DON’T:
- Exercise just before going to bed.
- Engage in stimulating activity just before bed, such as playing a competitive game, watching an exciting program on television or movie, or having an important discussion with a loved one.
- Have caffeine in the evening (coffee, many teas, chocolate, sodas, etc.)
- Read or watch television in bed.
- Use alcohol to help you sleep.
- Go to bed too hungry or too full.
- Take another person’s sleeping pills.
- Take over-the-counter sleeping pills, without your doctor’s knowledge. Tolerance can develop rapidly with these medications
- Take daytime naps.
- Command yourself to go to sleep. This only makes your mind and body more alert.
TREATMENT OF SNORING / OBSTRUCTIVE SLEEP APNEA
Medical Treatment
Conservative measures include weight loss, sleeping on one’s side, avoid smoking, alcohol, avoid being sleep deprived, and start a regular exercise regime.
Nasal Continuous Positive Airway Pressure (CPAP) is a non-invasive method of treatment, it entails using continuous positive airway pressure by a nasal mask worn by the patient throughout the night. CPAP is the most effective and frequently used treatment for OSA, but the issue of compliance is a major problem.
Oral Appliances (OA) are mouthpieces that are worn while sleeping to prevent the airway from collapsing. It works by repositioning the tongue or mandible forward.
Surgical Treatment
Simple snoring is considered a social disease with no medical significance. There are a number of treatment modalities, the efficacies of which are pretty similar but differ mainly in pain outcomes and costs. The majority of simple snoring is secondary to palatal flutter. Thus, treatment is directed at causing scarring in the soft palate. The theory is that the more collagen deposited into the soft tissues, the stiffer they are and the less likely to flutter.
With the advent of minimally invasive procedures, many newer office based techniques have been introduced. The Anterior Palatoplasty was introduced by myself, Dr Kenny Pang, for the treatment of snoring and mild OSA, has been shown to have good long term (three year results) in a multi-center trial (Singapore, Malaysia and America). This procedure can be an office-based, day procedure, done under local anaesthesia with minimal pain, short recovery time and can be done under 20 minutes. The results have been encouraging.
Surgical treatment of OSA can range from reduction of soft tissues in the mouth to enlarging the skeletal framework of the jaw. The latest Pang’s Expansion Pharyngoplasty (which I also invented) have been shown to be superior to the traditional uvulopalatopharyngoplasty (UPPP) operation. In a randomized trial, it showed a 86 per cent success rate in patients with palate and lateral wall collapse during sleep.
Surgical treatment results have been shown to be efficacious in treating both patients’ symptoms of tiredness, poor concentration, etc and reducing the number of apnoeas per hour.
Dr Kenny Peter Pang is an ENT / Sleep Specialist with MBBS, Masters Medicine (ORL), MRCS (Edinburgh), FRCS (Edinburgh), FRCS (Ireland) (OTO), FAMS (ORL). Dr Pang is the medical director of the Asia Sleep Centre located at Paragon #18-04. Call 6836 0060 to make an appointment or email drpang@asiasleepcentre.com. For more information about Dr Kenny Pang and the Asia Sleep Centre, go to www.drkennypang.com or www.asiasleepcentre.com.
