| LinkExchange Member | Free Home Pages at GeoCities |
| LinkExchange Member | Free Home Pages at GeoCities |
Send comments or suggestions to kerrinwh @ix.netcom.com
For some audience responses to date, CLICK HERE
To return to main page, CLICK HERE
Among healthy people, the most important determining factor of sleepiness is total sleep time; sleep restriction (i.e., chronic insufficient sleep) accounts for much of their sleepiness, and this is usually resolved by prolonging their sleep schedules. Also in people with mild-to-moderate sleep apnea, sleep time restriction has been said to worsen symptoms and sleep extension to improve them. The purpose of this study was to investigate sleep habits in a large sample of sleep apnea patients with a wide range of severity.
Data were gathered from 390 consecutive patients with excessive daytime sleepiness and complaints of snoring and/or episodes of breathing cessation during sleep. Of these were studied 268 patients who had routine polysomnography with a minimum of 5 apneas and hypopneas per hour (termed a respiratory event index or REI) and Multiple Sleep Latency Testing the next day. Their clinical evaluation included questioning about typical time in bed, estimated total sleep time, and estimated daytime sleep for weekdays vs. weekends.
Patients with shortened MSLT results of five minutes or less tended to be younger, but not to be more obese or have more frequent respiratory events. However, less severe apneics had less obesity and smaller neck size. Body Mass Index or BMI (see Glossary) was 33 (SD=7) in mild apneics (with REI of 5-20), 36 (SD=8) in moderate apneics (REI=21-60) and 39 in severe apneics (REI greater than 60). Corresponding neck sizes were 16 (SD=1), 17 (SD=1) and 18 (SD=1).
On polysomnography, sleep efficiency and sleep latency proved related to MSLT results, while sleep architecture, latency, and oximetry proved related to REIs. Subjective sleepiness proved related to MSLT results and, less consistently, to REIs.
With respect to sleep habits, time spent in bed on weekdays was significantly less in patients with shorter sleep latencies on MSLT. The same proved true of mild and moderate sleep apneics, but not severe sleep apneics, who spent more time in bed. Mild, moderate, and severe apneics did not differ in the frequency with which they reported napping (reported by 50-64% of patients), but those with severe sleep apnea reported longer naps than moderately and mildly ill patients, both on weekdays (37 minutes SD=48 vs. 24 SD=31 and 25 SD=35) and weekends (49 SD=51 vs. 35 SD=37 and 30 SD=41).
As the authors observed, their data suggested that among patients with mild to moderate degrees of obstructive sleep apnea, sleep habits (i.e., spending more time in bed and daytime napping) may help preserve better alertness (as indicated by MSLT results greater than 5 mins), but in severe sleep apneics such increased sleeping failed to affect daytime sleepiness. However, the authors admitted to uncertainty about the value of the MSLT and other measures used to measure daytime sleepiness, although patients with severe apnea did tend to present with more frequently with MSLTs of 5 or less than those with milder apnea. Sleep fragmentation was observed both as a result of sleep-disordered breathing and a correlate of daytime sleepiness; oximetry was related to respiratory event frequency but not to sleepiness.
The data in this study is presented in a relatively complex manner which can be much simplified. Basically, like healthy people, mild and moderate sleep apneics showed levels of daytime sleepiness that varied with the amount of sleep they reported at night. However, severe sleep apneics spent a lot of time in bed and napping without any apparent benefit to their daytime sleepiness. This suggests that in mild and moderate cases of sleep apnea, getting more sleep can help preserve alertness, but not so in severe cases, where the sleep fragmentation apparently overwhelms the ability of the body's usual sleep mechanisms to compensate.
It is interesting to consider that mild and moderate sleep apneics may benefit from the relatively simple measure of extending their sleep time. Or perhaps the situation should be viewed in the reverse perspective: that mild and moderate sleep apneics suffer from the common tendency of many healthy indviduals to voluntarily restrict their sleep in order to fit their sleep into their activity and work schedules, and would do better with a more adequate amount of sleep. On the other hand, with more severe apneics, amount of sleep appears largely irrelevant to degree of sleepiness. We can understand this better if we consider the previously discussed concept of sleep consolidation/fragmentation and the hypothesis that at least 10 minutes of continuous, uninterrupted deep sleep is necessary for its restorative effects. Milder sleep apneics probably experience this degree of continuity from time to time, and more so with longer intervals of sleep, whereas severe sleep apneics may never have the opportunity to experience this degree of continuity, no matter how much they sleep. This in turn indicates that, in severe sleep apnea, the first priority must be to lower the frequency of respiratory and other events fragmenting sleep. In mild to moderate sleep apneics, some benefits may be obtained from sleep hygiene measures.
WHAT DO YOU THINK ABOUT THIS ARTICLE AND MY COMMENTS?
CAN YOU RELATE THIS MATERIAL TO ANY PERSONAL EXPERIENCES?
Get your own Free Home Page