All of these mentioned situations are caused by phobias.
A phobia is a persistent, irrational fear that causes a person to feel intense anxiety. Phobias are the most common form of anxiety disorders. According to the American National Institute of Mental Health, nearly 10% of people suffer from one or more specific phobias.
The full list of phobias is almost limitless. It can be anything that someone could fear. However, some phobias are much more common than others. Here’s a top ten list of the most common phobias.
Acrophobia - Fear of Heights

Acrophobia in general is a fear of heights. Depending on the phobia's severity, an acrophobic person may fear being on a high floor of a building, or even climbing a ladder. It is sometimes confused with vertigo - a physical condition that causes dizziness or disorientation when looking down from a great height.
Claustrophobia - Fear of Enclosed Spaces

Claustrophobia is the fear of having no escape and being closed in places like: small rooms, locked rooms, cars, tunnels, cellars, elevators, subway trains, caves, and crowded areas
Nyctophobia - Fear of the Dark

It’s one of the most common children phobias. In most cases childhood nyctophobia passes when children grow up. This fear is probably a natural consequence of evolution, because night is the time when most predators hunt.
Ophidiophobia - Fear of Snakes

Like nyctophobia, some researchers believe that this phobia may be evolutionary developed by our ancestors as a survival mechanism. However, would not explain why snake phobias are relatively common, while fears of predatory animals, such as tigers, are rare. People who suffer from this phobia are not only afraid of touching snakes. They also show fear when viewing pictures of snakes or even talking about them.
Arachnophobia - Fear of Spiders

This one is extremely common. Sufferers generally fear spider webs and other signs that a spider may be nearby. They also fear pictures of spiders.
Trypanophobia - Fear of Injection or Medical Needles

Trypanophobia is a medical phobia. It may result in serious physiological responses including very low blood pressure and fainting. In some cases, severe trypanophobia may lead the sufferer to avoid all medical care.
Astraphobia - Fear of Thunder and Lightning

Like nyctophobia it is mostly common among children. Both adults and children tend to deal with the fear by seeking shelter, securing themselves in windowless areas where the storm cannot be seen.
Nosophobia - Fear of Having a Disease

It is the irrational fear of developing a disease. Sufferers may become frequent visitors of the doctor’s office, or may try avoiding doctors because of fear of hearing bad news.
Mysophobia/Germophobia - Fear of Germs

It is similar to nosophobia. It is an intense fear of becoming contaminated by germs. People suffering from this disease very often repetitively wash their hands to remove the contamination.
Triskaidekaphobia - Fear of the Number 13

This phobia unlike the others does not fit neatly into a clinical definition of a specific phobia. The number 13 is not an object or a situation, and it can be impossible for the sufferer to avoid. Nonetheless, triskaidekaphobia has actually influenced the modern world. For example, it is common the hotels or offices don’t have the 13th floor. Many people refuse to live in homes with a 13 in the address. Even public transportation is affected; some airplanes don’t have the 13th row
So, what are YOU afraid of?
Do you have any of the common mentioned phobias, or maybe you have a rare unusual one?
Have you heard of any unusual or even funny phobia?
Why do we even have phobias? Do you think they are something natural?