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Blog Feature

By: Kevin Asp on January 7th, 2016

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The Case of Sleep Onset with No Alpha Rhythm

Sleep Technologist Advice

Sleep Onset with No Alpha Rhythm

What happened in the case of a patient who was asleep with no alpha rhythm? 

You may think you can tell when someone falls asleep just by looking at them. But can you correctly point out the exact second he or she fell asleep? Chances are, not likely so.

In one of the AAST's Case of The Month learning modules, Dr. Rosenberg discusses a case involving a patient who had sleep study results that showed both respiratory events and periodic limb movements, but no alpha rhythm.

But before we offer more insight on obtaining a version of this module and listening to the case details yourself, let's define some of the key concepts that are involved in this Case of The Month on sleep onset with no alpha rhythm.

Defining sleep onset

Sleep onset is commonly defined as the transition from wakefulness into sleep. Sleep onset usually transitions into non-rapid eye movement sleep (NREM sleep) but under certain circumstances (e.g. narcolepsy) it is possible to transition from wakefulness directly into rapid eye movement sleep (REM sleep).

What are Alpha Rhythms?

When the functional state of the brain shifts from wake to sleep, the most reliable and accurate indicator of this sleep onset moment is a characteristic change in brain wave patterns.  The waking pattern is actually highly characteristic and generally shows what is known as an alpha rhythm.  A brain wave pattern qualifies as an alpha rhythm if its oscillation is between 8 and 12 cps (cycles per second, or hertz, as is now commonly used).

An interesting fact is that an alpha rhythm is present when we're awake, but is more enhanced and easier to detect when we have our eyes closed.  And because alpha waves are not present when we're sleeping, sleep technologists can easily identify the switch from wakefulness to asleep by seeing the change from alpha rhythm to no alpha rhythm.

That sounds like an easy job for the sleep technologist!

Well, not necessarily always. Some patients have a less prominent alpha rhythm that's difficult to detect, thus making the brain wave identification of sleep onset less precise.  But sleep onset can be unambiguously determined using brain waves and other markers in any case.  

 What does a no alpha rhythm EEG look like?

what-does-alpha-rhythm-look-like

In the AAST's Case of The Month on No Alpha Rhythm, you'll be able to learn the most about the following: a focused discussion on defining sleep onset in patients without alpha rhythm as well as discussion on the following: the rules for scoring limb movements in association with respiratory events, the rules for scoring RERAs, treatment strategies and the debate regarding the significance of isolated PLMS without RLS symptoms.

Interested in learning more about this case and earning a CEC?  Head over to our product page to view the module that's exclusively discounted for AAST members.

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