What is adrenaline?

Adrenaline, also called epinephrine, is a hormone released by your adrenal glands and some neurons.

The adrenal glands are located at the top of each kidney. They are responsible for producing many hormones, including aldosterone, cortisol, adrenaline, and noradrenaline. Adrenal glands are controlled by another gland called the pituitary gland.

The adrenal glands are divided into two parts: outer glands (adrenal cortex) and inner glands (adrenal medulla). The inner glands produce adrenaline.

Adrenaline is also known as the “fight-or-flight hormone.” It’s released in response to a stressful, exciting, dangerous, or threatening situation. Adrenaline helps your body react more quickly. It makes the heart beat faster, increases blood flow to the brain and muscles, and stimulates the body to make sugar to use for fuel.

When adrenaline is released suddenly, it’s often referred to as an adrenaline rush.

An adrenaline rush begins in the brain. When you perceive a dangerous or stressful situation, that information is sent to a part of the brain called the amygdala. This area of the brain plays a role in emotional processing.

If danger is perceived by the amygdala, it sends a signal to another region of the brain called the hypothalamus. The hypothalamus is the command center of the brain. It communicates with the rest of the body through the sympathetic nervous system.

The hypothalamus transmits a signal through autonomic nerves to the adrenal medulla. When the adrenal glands receive the signal, they respond by releasing adrenaline into the bloodstream.

Once in the bloodstream, adrenaline:

  • binds to receptors on liver cells to break down larger sugar molecules, called glycogen, into a smaller, more readily usable sugar called glucose; this gives your muscles a boost of energy
  • binds to receptors on muscle cells in the lungs, causing you to breath faster
  • stimulates cells of the heart to beat faster
  • triggers the blood vessels to contract and direct blood toward major muscle groups
  • contracts muscle cells below the surface of the skin to stimulate perspiration
  • binds to receptors on the pancreas to inhibit the production of insulin

The bodily changes that occur as adrenaline circulates throughout the blood is commonly called an adrenaline rush because these changes happen rapidly. In fact, they happen so fast that you might not even fully process what is happening.

The rush of adrenaline is what gives you the ability to dodge out of the way of an oncoming car before you’ve had a chance to even think about it.

Activities that cause adrenaline rush

Although adrenaline has an evolutionary purpose, some people take part in certain activities just for the adrenaline rush. Activities that can cause an adrenaline rush include:

  • watching a horror movie
  • skydiving
  • cliff jumping
  • bungee jumping
  • cage diving with sharks
  • zip lining
  • white water rafting

An adrenaline rush is sometimes described as a boost of energy. Other symptoms include:

  • rapid heart rate
  • sweating
  • heightened senses
  • rapid breathing
  • decreased ability to feel pain
  • increased strength and performance
  • dilated pupils
  • feeling jittery or nervous

After the stress or danger is gone, the effect of adrenaline can last up to an hour.

While the fight-or-flight response is very useful when it comes to avoiding a car accident or running away from a rabid dog, it can be a problem when it’s activated in response to everyday stress.

A mind full of thoughts, anxiety, and worry also stimulates your body to release adrenaline and other stress-related hormones, like cortisol (known as the stress hormone).

This is especially true at night when you lie in bed. In a quiet and dark room, some people can’t stop focusing about a conflict that happened that day or worrying about what’s going to happen tomorrow.

While your brain perceives this as stress, real danger isn’t actually present. So this extra boost of energy you get from the adrenaline rush has no use. This can leave you feeling restless and irritable and make it impossible to fall asleep.

Adrenaline may also be released as a response to loud noises, bright lights, and high temperatures. Watching television, using your cellphone or computer, or listening to loud music before bedtime can also contribute to a surge of adrenaline at night.

It’s important to learn techniques to counter your body’s stress response. Experiencing some stress is normal, and sometimes even beneficial for your health.

But over time, persistent surges of adrenaline can damage your blood vessels, increase your blood pressure, and elevate your risk of heart attacks or stroke. It can also result in anxiety, weight gain, headaches, and insomnia.

To help control adrenaline, you’ll need to activate your parasympathetic nervous system, also known as the “rest-and-digest system.” The rest-and-digest response is the opposite of the fight-or-flight response. It helps promote equilibrium in the body, and allows your body to rest and repair itself.

Try the following:

  • deep breathing exercises
  • meditation
  • yoga or tai chi exercises, which combine movements with deep breathing
  • talk to friends or family about stressful situations so you’re less likely to dwell on them at night; similarly, you can keep a diary of your feelings or thoughts
  • eat a balanced, healthy diet
  • exercise regularly
  • limit caffeine and alcohol consumption
  • avoid cellphones, bright lights, computers, loud music, and TV right before bedtime

If you have chronic stress or anxiety and it’s preventing you from getting rest at night, speak with your doctor or psychologist about anti-anxiety medications, such as selective serotonin reuptake inhibitors (SSRIs).

Medical conditions that cause an overproduction of adrenaline are very rare, but possible. A tumor of the adrenal glands, for example, can overstimulate the production of adrenaline and cause adrenaline rushes.

Additionally, for people with post-traumatic stress disorder (PTSD), memories of the trauma may elevate adrenaline levels after the traumatic event.