What the fight-or-flight response is doing, and why it sometimes runs without a real threat.
A panic attack involves the same physiological response as intense exercise. The heart rate, blood pressure changes, and adrenaline levels are within the range a healthy cardiovascular system handles routinely. The fear that it could be dangerous is part of what sustains the attack itself. The first time anyone has unexplained chest pain or rapid heart rate, an evaluation is the right step.
Yes. Nocturnal panic attacks wake people from sleep with a sudden surge of fear, racing heart, and shortness of breath. They aren't nightmares. They are the same physiological event as a daytime attack, beginning in deeper sleep stages. They aren't dangerous, though they often feel more alarming because they arrive without context.
The body's automatic preparation for action in the face of a perceived threat. The sympathetic nervous system releases adrenaline and noradrenaline within seconds, producing faster heart rate, tighter chest, faster breathing, redirected blood flow, sharper attention, and dilated pupils. The response is useful for a brief physical emergency and less suited to the chronic, low-grade threats most modern life produces.
Under high autonomic activation, the brain reduces the depth of sensory integration. The regions that normally bind sight, sound, and bodily sensation into a felt sense of being present become temporarily less coordinated. This produces derealization (the world feels unreal) or depersonalization (you feel detached from your own body). Insight is preserved, you know the experience is unusual, which distinguishes it from psychosis.
Most strategies that help during a panic attack don't actually stop the attack, the attack ends because the body can't sustain the surge. The strategies prevent the person from making the attack bigger. A long exhale (in for four, out for six or seven), light movement, and a deliberate decision to stop checking the pulse or scanning the body all reduce the activation. The attack still ends on its own. The interventions make the experience less awful while it does.