Halloween is that time of year when getting frightened becomes very popular. When you get scared, like when you watch a scary movie or visit a haunted house, your body has some important reactions. Luckily, none of these changes hurt your health in any way and some may even be helpful.

When you are suddenly scared, your body reacts by releasing hormones that cause your heart to beat faster and your breathing to quicken. Other hormones called endorphins are also released to help ease pain, reduce stress and alter your mood. It’s your body’s way of responding to a threat or very stressful situation (even if the threat isn’t real). The changes in your body are designed to give a greater sense of alertness and a burst of energy just when you need it most. Scientists call it the fight-or-flight response. According to researchers at the National Institute of Mental Health, it’s a key way we protect ourselves from danger and harm.

There can be beneficial effects to experiencing short, intense bouts of fear. Antioxidants are released within our body that help strengthen our immune system. In addition, the hormones oxytocin and dopamine are released when we encounter stress. These hormones give us a sense of pleasure and can help us feel closer to those around us. (No wonder horror movies have been a popular choice for a first date for so long.)

For most people, experiencing mild to moderate levels of fear such as watching a scary movie is fine health-wise. However, those with a heart condition may want to avoid watching the latest new horror film. In this case, increasing your heart rate or blood pressure is not a good idea.

While short bouts of fear don’t cause health problems for most of us, chronic stress or fear is another matter. It can lead to serious conditions such as severe anxiety or panic disorders. According to the National Institute of Child Health and Human Development, chronic stress can also affect your health in other ways. It can cause you to gain weight and even increase your risk of a heart attack, stroke, depression and other illnesses. So, enjoy that scary movie or haunted house outing – maybe just not every day!