As the name suggests, OHS usually affects people who are overweight or obese.
Hypoventilation means that breathing is too shallow or too slow. Because your body needs to work harder to breathe, your respiratory system* becomes exhausted and you end up with carbon dioxide levels that are too high and oxygen levels that are too low.
If you have OHS you might be experiencing:
shortness of breath
Excessive Daytime Sleepiness (EDS)
*Your respiratory system is made up of all the organs in your body that help you to breathe.