Here is an interesting article about changes in facial appearance after CPAP treatment for obstructive sleep apnea (OSA). Researchers took 20 subjectively sleepy subjects diagnosed with OSA but not treated. They took detailed photographs using specialized digital photography techniques before and after several months of CPAP treatment. They then had 22 raters look at the before and after treatment photos to assess which ones were post-treatment and what changes were present.
The results showed that treatment with CPAP is rated as more alert, more youthful, and more attractive than before CPAP use. In this study, the researchers had the subjects subjectively rate their level of sleepiness. As expected, sleepiness levels did improve overall. However, there was not a strong correlation between the person feeling more alert and being perceived more alert by the raters. This may be because the subjective scale for sleepiness is limited, and perhaps an objective measure of sleepiness may have correlated better.
Finally, the results did not support the popular belief that dark, swollen, and baggy circles under the eyes are a main feature of sleepiness in those with OSA. Of course, it could be a feature in those who are sleepy from other causes, like sleep deprivation.
Since adherence to CPAP is not great, perhaps the results of this study will provide more motivation for individuals to use their CPAP regularly.