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Sleep Disorders

Sleep study results and hypnotics

07/01/2008

Question:

Hi! I recently had a sleep study done and the report showed that I had an increased amount of alpha, spindles and "on occasion beta frequency EEG was present." On the report they believed it to be "secondary to previous or current hypnotics consumption." However, I am not nor have I been on anything remotely like a hypnotic. In fact, I don`t even take vitamins. I don`t think they believed me and I am worried that they may have missed a diagnosis because they probably assumed I was lying. I am curious what else could cause these results and what do they mean exactly?

Answer:

Alpha frequency is a normal EEG frequency, usually present when we are awake with the eyes closed. Alpha indicates resting wakefulness. Beta frequency on EEG is also a normal EEG finding in awake individuals when the eyes are open, or the person is focused, intense, or thinking. The presence of alpha and beta activity on EEG during a sleep study is normal and expected. These frequencies basically denote wakefulness. If a sleep study shows excessive amounts of alpha or beta activity, it usually represents the presence of excessive wakefulness during a sleep study and could be due to a number of factors, including difficulty acclimating to the sleep lab environment, underlying insomnia, or another sleep disorder, such as sleep apnea.

Sleep spindles are also normal type of brain activity, present mainly during non-dream (nonREM or NREM) stage II sleep. It has been reported that these spindles are "longer" or more "frequent" in patients who are concurrently using benzodiazepines, a class of sedative-hypnotic medications. It is, however, very difficult to objectively determine what the "normal" range of recurrence of sleep spindles is and thus most sleep physicians make this observation based on subjective interpretation. As such, the sleep physician typically does not attach a great deal of importance to this observation with regards to clinical decision making. They may make a note that this finding, while not absolutely indicative of, is consistent with the use of benzodiazepine-type of medications. The purpose of this observation is to remind the sleep physician to place the sleep study findings in the context of the patient's medical history, medication use and symptoms. It should be noted that patients may manifest "excessive" amounts of spindles without being on any medications. In addition, there are now medications other than benzodiazepines in the "hypnotic" class of drugs that may not have this effect on sleep spindles.

You should discuss your concerns with your sleep physician. Upon obtaining additional information from you, they should be able to place the sleep study findings in the appropriate clinical context and will work with you on identifying the cause of the symptoms that prompted the sleep study from the first place.

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Response by:

Rami N Khayat, MD Rami N Khayat, MD
Clinical Associate Professor of Pulmonary, Allergy, Critical Care & Sleep
College of Medicine
The Ohio State University