Diagnostic Methods
The taking of a thorough medical history while keeping in mind alternative diagnoses and the possibility of more than one ailment in the same patient is the first step. Symptoms for very different sleep disorders may be similar and it must be determined whether any psychiatric problems are primary or secondary.
The patient history includes previous attempts at treatment and coping and a careful medication review. Differentiation of transient from chronic disorders and primary from secondary ones influences the direction of evaluation and treatment plans.
The Epworth Sleepiness Scale (ESS), designed to give an indication of sleepiness and correlated with sleep apnea, or other questionnaires designed to measure excessive daytime sleepiness, are diagnostic tools that can be used repeatedly to measure results of treatment.
A sleep diary, also called sleep log or sleep journal, kept by a patient at home for at least two weeks, while subjective, may help determine the extent and nature of sleep disturbance and the level of alertness in the normal environment. A parallel journal kept by a parent or bed partner, if any, can also be helpful. Sleep logs also can be used for self-monitoring and in connection with behavioral and other treatment. The image at the top of this page, with nighttime in the middle and the weekend in the middle, shows a layout that can aid in noticing trends
An actigraph unit is a motion-sensing device worn on the wrist, generally for one week. It gives a gross picture of sleep-wake cycles and is often used to verify the sleep diary. It is cost-efficient when full polysomnography is not required.
Polysomnography is performed in a sleep laboratory while the patient sleeps, preferably at his or her usual sleeping time. The polysomnogram (PSG) objectively records sleep stages and respiratory events. It shows multiple channels of electroencephalogram (EEG), electrooculogram (EOG), electrocardiogram (ECG), nasal and oral airflow, abdominal, chest and leg movements and blood oxygen levels. A single part of a polysomnogram is sometimes measured at home with portable equipment, for example oximetry, which records blood oxygen levels throughout the night. Polysomnography is not routinely used in the evaluation of patients with insomnia or circadian rhythm disorders, except as needed to rule out other disorders. It will usually be a definitive test for sleep apnea.
A Multiple Sleep Latency Test (MSLT) is often performed during the entire day after polysomnography while the electrodes and other equipment are still in place. The patient is given nap opportunities every second hour; the test measures the number of minutes it takes from the start of a daytime nap period to the first signs of sleep. It is a measure of daytime sleepiness; it also shows whether REM sleep is achieved in a short nap, a typical indication of narcolepsy.
Imaging studies may be performed if a patient is to be evaluated for neurodegenerative disease or to determine the obstruction in obstructive sleep apnea.
Read more about this topic: Sleep Medicine
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