Untreated excessive daytime sleepiness (EDS) results in compromised quality of life, reduced productivity, and public safety concerns.1 Obstructive sleep apnea (OSA), restless legs syndrome, circadian rhythm disorders, and narcolepsy are frequently underdiagnosed sleep disorders that can cause EDS. These conditions commonly go undetected and untreated for several reasons:
- Patients may not recognize sleepiness as a legitimate medical concern.
- Physicians, with few exceptions, typically have little training in sleep disorders and limited time to diagnose them.2 Screening questions regarding sleep are typically absent.
- Definitive diagnostic tests are costly.
As a result, many patients go without appropriate sleep evaluations. Instead a depressive or other psychiatric disorder may be suspected because of the sleepy patient’s poor energy, hypersomnia, amotivation, irritability, and frustration. Because of ongoing behavioral symptoms, patients with an undiagnosed primary sleep disorder are often referred to psychiatrists. Thus, a clear understanding of the differential diagnosis of EDS is crucial.
Patients with sleep issues fall into three major categories:
- Patients with EDS.
- Individuals with insomnia, another large group often seen by psychiatrists. Generally, these patients are less hesitant than patients with EDS to seek help because of the marked distress they suffer nightly when trying to sleep. Insomniacs typically experience minimal EDS.
- Patients with unusual behaviors at night that range from arm waving to violent behaviors.
Assessing the sleepy patient
When evaluating a patient with sleep complaints, several valuable sources of data come into play.
Initially, observe the patient in the waiting room or office before starting the interview. Did the patient nod off while waiting for his or her appointment? Pay attention to any patient who appears sleepy—even if he or she denies having trouble staying awake. Over time, sleepy patients may have lost their perspective on alertness. Some patients have had EDS for so many years that they no longer recall what it is like to feel fully awake.
Collateral history is often important because family members generally observe the sleeping patient. The bed partner often provides valuable information about snoring, irregular breathing leg kicks, unplanned naps, and strained interpersonal relationships due to EDS. For the patient who does not have a bed partner, ask his or her travel companion, with whom the patient may have shared accommodations.
Unfortunately, few useful screening tests exist. Most questionnaires about sleepiness are neither very reliable nor valid. One of the better questionnaires, the Epworth Sleepiness Scale, helps confirm the presence of sleepiness with a score <8, differentiating the inability to stay awake from fatigue. (Box 1 can be cut out, copied, and handed to patients). This brief questionnaire also provides a useful measure of severity.3
The value of the Epworth scale is limited, however, because patient answers often are based on a specific time and context that may not be representative. Additional validated surveys include the Pittsburgh Sleep Quality Inventory and several that focus on OSA.4
EPWORTH SLEEPINESS SCALE
How likely are you to doze off or fall asleep in the following situations, in contrast to feeling just tired? 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 (e.g., a theater or a meeting) |
| ○ | Sitting 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 |
| Johns, M. Sleep 14:540-545, 1991. | |
Electroencephalographic (EEG) monitoring can accurately measure the patient’s degree of sleep disruption. This information is critical in understanding if a patient’s EDS is caused by a physiologic condition that prevents quality nocturnal sleep. At this time, however, no portable devices that employ EEG technology are used in clinical settings.
Additionally, none of the widely used screening devices that assess leg kicks indicate the presence of possible periodic limb movements.
Even though overnight pulse oximetry has been used to screen for sleep-disordered breathing,5 the technology has limitations. For one, most pulse oximeters do not provide information about sleep stage or body position. Some patients with significant sleep-disordered breathing lack adequate oxygen desaturations but have frequent EEG arousals due to sleep issues. In this case, pulse oximetry would generate a false negative result because EEG data is not collected. The inadequate sensitivity is most likely to occur with females and thin patients.