Sleep Study Tests
Many tests are available to assess the quality of an individual’s sleep, and a discussion of each is beyond the scope of this course. However, the most commonly used tests are polysomnography and the multiple sleep latency test (MSLT), both of which are used in the evaluation of many sleep disorders.
Polysomnography is preferably conducted by a certified sleep technologist at an AASM-accredited facility. This test monitors many physiologic parameters, including electrocardiogram, EEG, eye movements (electrooculogram), chin EMG, airflow, oxygen saturation, respiratory effort, and heart rate.
A technician will note if snoring is present and, if so, the degree (i.e., mild, moderate, or severe). Body position and leg EMG derivations are also recommended.
One full-night study is typical, but split-night studies (i.e., polysomnography followed by continuous positive airway pressure [CPAP] titration) may be used when initial monitoring shows a high apnea-hypopnea index (AHI) score. Polysomnography can help rule out the possibility of sleep disorders, and it will also show if the patient’s sleep cycle is normal or if REM sleep occurs at unusual times.
Portable monitor testing has a known likelihood of producing false-negative results; therefore, it is considered inferior to overnight sleep lab polysomnography. Airflow, blood oxygenation, and respiratory effort are the minimum test parameters needed for a complete at-home study. The sensors are similar or identical to those used for polysomnography and will either be placed by a sleep technologist, other trained professional, or the patient following detailed instruction.
The MSLT is a daytime test that can determine if REM sleep patterns occur during wakefulness and monitor the amount of time it takes for the patient to fall asleep normally during the day. For example, sleep latency periods (i.e., the time it takes to fall asleep) are typically 8 minutes or less in narcoleptic patients, but healthy individuals usually take 12 or more minutes to fall asleep during the daytime.
The American Psychiatric Association’s diagnostic criteria for Insomnia Disorder
The Diagnostic and Statistical Manual of Mental Disorders (DSM-5):
A. A predominant complaint of dissatisfaction with sleep quantity or quality, associated with one (or more) of the following symptoms:
- Difficulty initiating sleep.
- Difficulty maintaining sleep, characterized by frequent awakenings or problems returning to sleep after awakenings.
- Early-morning awakening with inability to return to sleep.
B. The sleep disturbance causes clinically significant distress or impairment in social, occupational, educational, academic, behavioral, or other important areas of functioning.
C. The sleep difficulty occurs at least 3 nights per week.
D. The sleep difficulty is present for at least 3 months.
E. The sleep difficulty occurs despite adequate opportunity for sleep.
F. The insomnia is not better explained by and does not occur exclusively during the course of another sleep-wake disorder (e.g. narcolepsy, a breathing-related sleep disorder, a circadian rhythm sleep-wake disorder, a parasomnia).
G. The insomnia is not attributable to the physiological effects of a substance (e.g.a drug of abuse, a medication).
H. Coexisting mental disorders and medical conditions do not adequately explain the predominant complaint of insomnia.