Poor energy, hypersomnia, amotivation, irritability, and frustration can suggest depression or other psychiatric disorders to busy primary care physicians. As a result, psychiatrists often are referred patients with excessive daytime sleepiness (EDS) caused by undiagnosed primary sleep disorders.
Physicians may miss obstructive sleep apnea (OSA), restless legs syndrome, circadian rhythm disorders, or narcolepsy because:
- many have little training in sleep disorders and limited time to diagnose them1
- patients do not report sleepiness or recognize it as a legitimate medical concern
- definitive diagnostic tests are expensive and usually are not ordered.
Psychiatrists, therefore, need a clear understanding of the EDS differential diagnosis to determine whether a patient’s behavioral symptoms are a sleep or psychiatric issue.
Epworth Sleepiness Scale
How likely are you to doze off or fall asleep in the following situations, in contrast to feeling just tired? This refers to your usual way of life in recent times. Even if you have not done some of these things recently, try to work out how each situation would affect you now. Use the scale below to choose the most appropriate number for each situation:
0 no chance of dozing
1 slight chance of dozing
2 moderate chance of dozing
3 high chance of dozing
Chance of dozing Situation
Sitting and reading
Watching TV
Sitting inactive in a public place (such as in a theater or a meeting)
As a passenger in a car for an hour without a break
Lying down to rest in the afternoon when circumstances permit
Sitting and talking to someone
Sitting quietly after a lunch without alcohol
In a car, while stopped for a few minutes in traffic
Scoring key
1 to 6 Getting enough sleep
7 to 8 Average
>8 Seek a sleep specialist’s advice without delay
Assessing the sleepy patient
Sleepiness is an inability to stay awake at appropriate times. Fatigue, by comparison, does not involve sleepiness but very low energy associated with wakefulness. In general, sleepy patients get transient relief from napping, whereas fatigued patients report they cannot fall asleep.
Untreated EDS results in compromised quality of life, reduced productivity, and public safety concerns such as falling asleep while driving.2 Sleep complaints fall into three major categories:
- EDS
- insomnia (marked by distress because of poor sleep, but usually with minimal EDS)
- unusual nocturnal behaviors (ranging from arm waving to violent behaviors.
When you evaluate a patient with sleep complaints, valuable sources of data include observation, questionnaires, and screening devices. The most important may be common sense.
Observation. Observe the patient in the waiting room or office before starting the interview. Did he or she nod off while waiting to see you? Pay attention to anyone who appears sleepy—even those who deny having trouble staying awake. Over time, sleepy patients can lose their perspective on alertness. Some have had EDS so long that they no longer recall what it is like to feel fully awake.
Collateral history often is important because family members probably have observed the sleeping patient. The bed partner can provide information about snoring, irregular breathing, leg kicks, unplanned naps, and strained interpersonal relationships because of EDS. For the patient without a bed partner, consider interviewing a travel companion.
Questionnaires. Few useful screening tests exist for sleepiness; most are neither reliable nor valid. One of the better questionnaires—the Epworth Sleepiness Scale (Box 1)—helps confirm the presence of sleepiness with a score >8, differentiating the inability to stay awake from fatigue. This brief questionnaire also provides a useful measure of sleepiness severity.3
The Epworth scale’s value is limited because its questions of specific time and context might not represent a patient’s experiences. Additional validated surveys include the Pittsburgh Sleep Quality Inventory and several for sleep apnea.4
Screening. Electroencephalographic (EEG) monitoring can accurately measure the patient’s degree of sleep disruption. This information is key to understanding if a patient’s EDS is caused by a physiologic condition that prevents quality nocturnal sleep.
None of the widely used screening devices that assess leg kicks indicate the presence of possible periodic limb movements.
Overnight pulse oximetry has been used to screen for sleep-disordered breathing5 but also has limitations:
- Most pulse oximeters do not provide information about sleep stage or body position.
- Patients with sleep-disordered breathing can lack adequate oxygen desaturations but have frequent EEG arousals related to sleep issues. Because EEG data are not collected during arousals, pulse oximetry would generate a false-negative result in this scenario, which occurs most often in female and thin patients.
- Oximetry provides only oxygen saturation data and possibly heart rate, whereas other physiologic processes such as body movement or sleep architecture can be disrupted repetitively during sleep.
Common sense. The most productive tools for detecting sleep disorders are intuition and common sense. The Figure suggests sequential questions that might uncover specific sleep disorders. Then the decision whether to refer the patient to a sleep disorder center for diagnostic testing depends on the type of sleep disorder you detect.