Hi, I understand your concern. The reason for the nocturnal awakenings in sleep apnoea as you may have read, is the lack of oxygen (hypoxia) supply to the lungs/body due to partial and prolonged obstruction of the airway. A relative state of hypoxia drives the individual out of his sleep, making him feel suffocated and aroused, hence experiencing the other symptoms of autonomic arousal in the body. When pushed to such stressors (as the hypoxia), our bodies respond by activation of the sympathetic system and increase in levels of those molecules in bloodstream, which will increase the alertness, heart rate, breathing rate and cause sweating or tremors (adrenaline/catecholamines). On the other hand, a panic attack per se is defined as an episode of intense anxiety that manifests with the same symptoms as the autonomic arousal mentioned above. Thus, the experience of panic attack intrudes the patient s sleep due to the apnoea. This points out that the nocturnal panic attacks appear to be a part of the sleep apnoea syndrome for the patient, where the symptoms of arousal resemble a panic attack. Some clinicians choose to label these attacks separately for the ease of communicating a diagnosis. But eventually it does not make significant implication on further management or care, unless the patient is experiencing such panic attacks even during the day hours. I hope this clarifies your doubt. Please feel free to ask any more questions.