Although some may compare a sleep apnea headache to a migraine, there are actually some distinctive differences for most sufferers. For instance, they are usually felt on both sides of your head, whereas a migraine tends to occur on just one.
Likewise, a sleep apnea headache tends to be at its worst when you first wake up and then gradually get better as your sinuses open and you begin to breathe without obstruction, typically fading away completely in around an hour or so.
You’ll also find that a sleep apnea induced headache occurs on a far more regular basis than a migraine, which tends to be less frequent but lasts for hours, if not days when they are experienced.
Other signs that indicate you’re suffering from a migraine and not a sleep apnea related ailment are if you also feel nauseous or vomit, and if you experience blurred vision or sensitivity to light, as these symptoms should not occur from using a CPAP.
In order to determine whether it is the CPAP causing your headaches, it might be worth making a note of when you experience the symptoms and what exactly they are. This will help you present your case if you need to visit a doctor or your ENT.