Sleep Fragments

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Can you determine which medication a patient is taking?

Contributed by James A. Rowley, MD, Wayne State University School of Medicine, Detroit,

Which class of medications is associated with the EEG pattern in the fragment below?

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  1. This record demonstrates an epoch of N2 sleep, with very frequent spindles seen in the EEG leads (see answer fragment below). This is a frequent finding with benzodiazepine medications. Sleep spindles can also be seen with barbiturates and alcohol.
  2. Benzodiazepines have the following effects on sleep stages and architecture: decreased sleep latency, fewer stage changes, decreased stage N1 sleep, increased stage N2, increased sleep spindles, decreased Stage N3 sleep and decreased Stage R (REM) sleep. However, there may be an increase in the number of REM cycles during the night. 
  3. Note that the non-benzodiazepines sedatives such as zolpidem and zaleplon are not associated with excessive sleep spindles.  In addition, they have only mild suppressant effects on Stage R sleep and do not decrease Stage N3 sleep. .


  1. Qureshi, A., and Lee-Chiong, T. (2004) Medications and their effects on sleep.Medical Clinics of North America 88, 751-766


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