Here\u2019s the scenario. Your house loses power. You hear a creaky noise coming from upstairs. You swear someone is whispering your name. A shadow creeps up from behind. You become so scared that you can\u2019t move. Your heart races. You feel a rush of adrenaline. You\u2019re ready for whatever might be coming for you. But then the lights come back on and you realize your dog is upstairs and your friend has been calling your name from the bathroom. All goes back to normal and you laugh it off. But what just happened is the result of your brain taking the necessary actions to help you survive, should that monster have been real.\nSo what actually happens?\nYour brain\u2019s window to the world, also known as the thalamus, receives sensory input from your eyes, ears and other sources. When your brain perceives fear or a threat, signals are sent from the thalamus to two regions of the brain \u2013 the amygdala and hypothalamus.\nWhen the signal reaches the amygdala \u2014 a region near the base of the brain that plays a key role in processing emotions and is linked to fear responses and pleasure, it releases a brain chemical called glutamate, which makes you freeze or involuntary jump. This is a known evolutionary response that is designed to keep you hidden from any potential danger, like that ghost lurking in the attic.\nNow, here comes the part that makes you feel like Superman. When the signal reaches the hypothalamus, a portion of the brain that maintains the body\u2019s internal balance and helps regulate and produce hormones, it elevates your blood pressure and heart rate and pumps adrenaline throughout your body. This is a key component to your body\u2019s \u201cfight or flight\u201d response \u2013 an evolutionary adaptation that allows you to react to fear or danger quickly.\nThe adrenaline increases blood flow to the muscles, giving you a surge of increased physical strength. The adrenaline also increases oxygen to the lungs, allowing you to run faster than you normally would. Your ability to feel pain also decreases. Basically, your body is prepared for whatever might try to attack or scare it \u2013 whether it\u2019s a werewolf or a mouse.\nLuckily, for most of us, we don\u2019t need to kick into the fight or flight mode very often. After the initial fear response turns out to be just a bug you didn\u2019t know was there, the parasympathetic nervous system reverses the flow of adrenaline and lowers your heart rate back to normal.\nSo the next time you think you spot a ghost or goblin, or a house centipede, remember it\u2019s your brain causing you to run faster, jump higher and lift cars. Well, maybe not cars, but very heavy things.