We all know that feeling you get when you hear a strange sound in the middle of the night: your heart races, your eyes dilate, your entire body tenses. Whether the sound turns out to be an intruder or just your dog moving around in the other room, what you are experiencing is fear. We know it affects the mind, but in addition, fear impacts your health in some surprising ways.

Inability to Relax

Thinking back to that hypothetical noise you heard in the introduction, remember how you usually feel once the sound stops. You rarely feel rested or comfortable -- even if you are relieved to find that the sound was just your pet, you will most likely still be awake for a while. Once the body experiences the fear response, it is slow to relax. It is preparing itself for the next sound or the next time it needs to get ready to fight or flee, which makes it very difficult for you to settle afterward. This only gets worse when the fear sensation is very strong or continues for a very long time.

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Anxiety and Panic

Anxiety is often situation-based, and is, in simple terms, often a fear of the body's reaction to fear. If a person feels fear when giving a speech in front of their oral communications class, for instance, they may in future associate such situations with fear, and avoid giving speeches as often as possible. This can lead to anxiety (sweaty palms, a racing heart, or nausea) or even an anxiety disorder, which can then manifest itself as panic attacks when one is in a situation that reminds them of the one that prompted their fear.

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Weakens Immune System

The body's fear response includes an upsurge of adrenaline and cortisone. Long-time exposure to these chemicals and other related hormones can take a toll on the immune system, making it weaker and less able to fight off infections, viruses, or other illnesses. While fear does not directly cause you to get sick (in most cases), prolonged fear does not put the body in the best position to defend itself from the germs that would like to invade it.

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Sharpens Survival Instincts

When one is afraid, their body carries out what is known as the fight or flight response. This is a primitive instinct handed down to us from our ancestors, who often had to decide whether to fight off a predator was coming for them or run the other way. When we get scared, our heart races and all of the blood moves from our extremities to the core of our body, so that the most vital functions can continue to be carried out as we run or fight for our lives. For some people, the sensations this causes can be just as scary as the situation itself.

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Being scared for an extended period can lead to not only anxiety but also depression, near-constant feelings of sadness, moodiness, and fatigue. When caused by fear, depression occurs most often in people who feel these sensations on a daily basis and feel they cannot do anything about it, such as someone who has a phobia of elevators but must take an elevator to their office every day.

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Prolonged fear about a particular object or situation can eventually lead to a phobia of that object or situation. Bad experiences, such as getting bitten by a spider, can cause phobias, or they can seem to develop without cause, like a fear of birds even when one has never been harmed by one. Phobias can quickly expand, leaving an individual afraid of not just of the type of spider that bit them, but of all spiders, or even of insects in general.

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Heart Damage

Perhaps one of the most detrimental bodily effects of fear is damage to the heart and cardiovascular system. Heightened fear on a long-term basis can eventually -- after months or years -- lead to serious heart problems. The organ becomes overworked and stressed from the constant bombardment of stress hormones and ceases to function properly. Luckily, as this happens over time, there is always a chance to reverse this damage before it starts or grows serious.

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Lack of Confidence

If one is afraid much of their time, this can leave them feeling less confidence. People who experience fear regularly often begin to turn in on themselves as their self-confidence shrinks to minuscule levels. This can lead to not only missed opportunities but also depression and anxiety.

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Missing Out

Fear can make people miss out on doing things that might be good for them. Not only might they skip directly health-related events such as medical check-ups, but they may also avoid friend or family gatherings and other activities important to overall well-being. 

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Worsens Memory

Finally, fear can negatively impact memory. The brain is so busy getting ready to fight or flee that it doesn't record memories as effectively, and it often can't concentrate on anything except the fear it is feeling. The body is trying to protect you with these processes, but in the end, it only leaves you more worried, scared, and scattered.

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