Q. How do sleep disorder centers evaluate patients?
A. Among the tests used by accredited sleep disorder centers is overnight nocturnal polysomnography. This test consists of videotaping and simultaneous monitoring of the electroencephalogram (EEG); electro-oculogram; electromyelogram (EMG), usually of the chin, leg (anterior tibialis), and sometimes intercostal muscles; nasal/
oral airflow; respiratory effort; snoring; body position; oxygen saturation; and cardiac function. Numerous modifications of the basic polysomnographic montage may be made if there are special diagnostic considerations. Variations may include additional EEG leads to evaluate for epileptiform activity; additional EMG of other extremities, such as for rapid eye movement (REM) behavior disorder and other movement disorders; esophageal pressure monitoring for suspected upper airway resistance syndrome or sleep apnea syndrome; carbon dioxide monitoring for pulmonary patients or for children with snoring/sleep apnea syndrome; and nocturnal penile tumescence monitoring for impotence evaluation.
Polysomnography is usually done at night but should be performed during the patient’s normal sleep time, such as daytime testing for a night-shift worker. After adequate diagnosis, polysomnographic monitoring can continue with such appropriate treatments as continuous positive airway pressure (CPAP, room air); bilevel positive airway pressure (BiPAP); or administration of oxygen via nasal cannula, CPAP, or BiPAP. The effects of therapy are usually monitored during a second study night but may be assessed during the first study night in patients who have more severe sleep apnea or hypoventilation syndromes.
Outpatient office evaluation and outpatient overnight and daytime sleep studies performed in a laboratory are available by referral at accredited sleep disorder centers. A list of such accredited centers and board-certified sleep specialists is available from the American Academy of Sleep Medicine, One Westbrook Corporate Center, Ste. 920, Westchester, IL 60154; phone: (708) 492-0930; Web site: www.aasmnet.org.
Q. What other tests are available to help elucidate the diagnosis?
A. The multiple sleep latency test (MSLT) assesses the degree of daytime sleepiness and evaluates the patient for narcolepsy. An MSLT result of 10-20 minutes is a conventionally established normal level of daytime sleepiness. An MSLT of five to 10 minutes demonstrates a mild to moderate level of daytime sleepiness. An MSLT of zero to five minutes indicates a severe pathologic level of daytime sleepiness. Patients with results at this level are in potential danger of experiencing uncontrollable microsleeps or sleep attacks. Narcoleptics have abnormal MSLTs and also demonstrate REM sleep during MSLT testing. Because patient self-assessment of sleepiness is often inaccurate, an MSLT can assist the clinician in differentiating between fatigue and true sleepiness complaints and in quantifying a patient’s sleepiness by EEG criteria rather than subjective reports.
A maintenance of wakefulness test (MWT) is similar to the MSLT but assesses the patient’s ability to stay awake. This test may be ordered in transportation workers, such as pilots or train operators, to evaluate their ability to stay awake using EEG criteria. Normative MWT values are defined based on both 20- and 40-minute nap-opportunity protocols.
Q. Is there a treatment for patients with insomnia?
A. There is no single treatment for insomnia because insomnia is a description of difficulty in sleeping rather than a diagnosis. Insomnia is a symptom based on a large number of sometimes simultaneous potential disorders. Therapy for insomnia is determined by first making a diagnosis based on history, exam, and possibly additional testing. Several causes of insomnia frequently coexist, especially if there has been insomnia for longer than weeks or months.
The many causes of insomnia can be categorized as being medical, based in sleep disorders, chemical, and psychiatric. Medical problems include hyperthyroidism, chronic lung disease, chronic renal disease, Parkinson’s disease, dementia, heart failure, reflux, and chronic pain. Possible causative sleep disorders are central sleep apnea, obstructive sleep apnea, periodic limb movement disorder, restless legs syndrome (RLS), and circadian rhythm disturbances. Insomnia-inducing agents include caffeine, alcohol, many cardiac drugs, most asthma drugs, steroids, most antidepressants, and dopaminergics; withdrawal from hypnotics can also result in insomnia. Finally, mood disorders, mania, anxiety, panic disorders, and alcohol and drug dependencies, as well as psychosis, can produce insomnia in some patients.
Q. Do some behaviors exacerbate insomnia?
A. Poor sleep hygiene is often a complicating cause that further entrenches insomnia problems. In an effort to treat their own insomnia, patients may develop poor sleep behaviors, such as staying in bed and becoming focused and anxious about not sleeping (psychophysiologic insomnia); drinking caffeine during the day to counteract the prior night’s sleeplessness; drinking alcohol near bedtime (once metabolized, alcohol causes awakenings); exercising too close to bedtime, rather than the ideal time of late afternoon or earlier; engaging in mentally stimulating activities too close to bedtime; or wakening and going to bed at inconsistent times.
Insomnia includes difficulty falling asleep, difficulty staying asleep, and early-morning awakening—complaints that may help guide the clinician in the investigation. Generally, difficulty initiating sleep is more likely to be seen in association with psychophysiologic insomnia, poor sleep hygiene, and such psychological problems as anxiety. Difficulty maintaining sleep is more likely associated with medical problems or sleep disorders. Early-morning awakening is seen in patients with various medical or sleep disorders and is also a symptom of depression.
In addition to a complete medical and medication history, as well as physical examination, the insomnia patient requires a detailed 24-hour sleep/wake history of habits and activities. Generally, an insomniac with resultant daytime sleepiness requires a more urgent and aggressive workup than does an alert insomniac.