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Sleep Disorders

Missing slow-wave sleep after OSA treatment

11/26/2007

Question:

I am a 43-yr old male. I was diagnosed with moderate obstructive sleep apnea 5 yrs ago, and have been sleeping with CPAP therapy ever since. Based on the symptoms I had ben having, though, I am convinced that I was an OSA sufferer for >20 years before that (ie, since I was about 14 or 15, based on my general tiredness, and complaints from others about my snoring/breathing cutoffs during sleep at that time). Based on subsequent sleep studies, the CPAP therapy appears to work in alleviating/eliminating the sleep apnea. However, it also shows that I am still missing stages 3&4 sleep, even under CPAP treatment. My sleep dr. tells me, that he doesn`t know why this happens, and has prescribed evening doses of 2 gm Tryptan + 25 mg Seroquel, to try to induce the deep level sleep. However, I continue to remain tired, and have memory lapses, even under this treatment (although there has been a slight improvement since starting the meds). A look online tells me, that there are a few sufferers of this problem out there, but this problem seems to not be well-understood at this time. Questions: 1. Are you aware of this type of a slow-wave sleep disorder/absence for long-time OSA sufferers? 2. Are there any new treatment options on the horizon, to help improve the % time spent in slow-wave sleep? Thanks

Answer:

This is an interesting question and brings up issues about the treatment of sleep apnea, the significance of slow wave sleep and the impact of trying to alter the type of sleep we get.

It’s possible that your residual sleepiness and fatigue may have more to do with your obstructive sleep apnea (OSA) and not with the amount of slow wave sleep you are getting. Even though the airway is kept open with CPAP on a sleep study, it’s still possible that arousals from sub-clinical respiratory events or arousals induced from other causes (such as periodic limb movement disorder) could fragment your sleep and lead to nonrestorative sleep. Addressing these issues would be important to get you sleeping and feeling your best.

Sleep Specialist are also beginning to realize that some patients with OSA, particularly those who have severe OSA that went undiagnosed for some time, may be at risk for permanent sleepiness due to subtle damage to the centers in the brain that control wakefulness. These individuals may remain sleepy even once their airway is kept open during sleep with CPAP and thus stimulant therapy may be beneficial in this setting.

Slow wave sleep (SWS), also know as deep sleep, appears to make up less and less of our sleep time as we age. For example, you children may spend up to 50% of their sleep time in SWS, whereas elderly individuals may spend 10% or less of their sleep time in SWS. The significance of this is unclear. We do know that SWS can be reduced in amount by certain conditions, such as OSA, as well as certain medications, such as benzodiazepines. In some individuals, treating OSA can improve the amount of SWS they get, but this is not always the case and the reason for this is not always obvious. It’s also not really known if the failure to restore “normal” amounts of SWS in patients with OSA has any significant consequences (for example, how sleepy they feel).

The use of medications to restore SWS has not been studied in well-done scientific studies at this point in time. Some drugs and medications, such as 5-hydroxytrytophan and Trazodone, have been shown in animal studies to increase the amount of SWS animals may get, but this has not yet been proven in humans. In addition, it’s not clear that artificially increasing the amount of SWS you get with medications will make you feel more rested.

There is plenty of research looking at OSA and medications. I am not personally aware of any studies at present that are specifically targeting SWS.

I recommend you re-discuss your situation with your Sleep Specialist. I would make sure the issues mentioned above regarding your OSA have been fully addressed. Using medications to try to improve the amount of SWS you are getting is unproven at this point in time and no current strategies are recommended.

If you would like information regarding sleep and sleep disorders, please do not hesitate to ask or, alternatively, you can obtain it on the American Academy of Sleep Medicine website. This website also contains a list of Sleep Centers across the country so you can locate one near you if need be. Good luck!

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Response by:

Dennis   Auckley, MD Dennis Auckley, MD
Associate Professor of Medicine
School of Medicine
Case Western Reserve University