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Stress and the Brain’s Response to It



Some of the more common symptoms of stress such as depression, anxiety, sleep disturbance, fatigue and outbursts of crying for no reason are caused by a chemical malfunction in the brain.

It can help to look at the way our brain chemicals function and are affected by stress so you know exactly what is happening to you.

Chemical Messengers:

Since 1977 scientists have been able to find out about the inner workings of the brain through being able to penetrate into the very interior of single nerve cells.

This work revealed that vital chemicals carry messages between brain cells which allow them to communicate with each other. Every day billions of such messages are being sent back and forth between the cells in the brain.

There are two different kinds of messengers and the messages they carry are the complete opposite of each other.

Their function is to either encourage or inhibit our feelings and behaviour, the ‘positive’ messengers and the ‘negative’ messengers if you will.

The positive ones send happy, uplifting and joyful messages and the negative messengers carry the less positive, less stimulating and sadder messages. The majority of our nerve centres receive input from both types of messengers and as long as this input is balanced between the two then everything runs along on an even keel.

There are three positive messengers in the brain: serotonin, noradrenalin and dopamine and it is these brain chemicals that begin to malfunction when stress levels become more than we can handle comfortably. They each have quite different functions:


Serotonin is essential for ensuring you get a good night’s sleep and when we are stressed this is often the first change we notice.

If serotonin is out of balance then restful sleep will elude you because it is responsible for the regulation of our internal body clock that makes sure the body is ready and receptive for sleep.

The body clock lives at the very centre of the brain in the Pineal Gland and it is in there that serotonin is stored ready for use by the body.

It is actually converted by the body into melatonin every day and then converted back again to serotonin over a 24 hour period and that is what decides your body clock.

This daily cycle is how your body chemistry is adjusted to a sleep and wake pattern so that when it is working optimally, the serotonin will make sure that each night you are drowsy and ready to sleep and maintains the sleep cycle throughout the night so that your sleep is deep and restful.

It is the switch to melatonin each morning that means you wake up rested and refreshed.

Our Internal body clock

As well as regulating our sleep patterns, our body clock is also responsible for co-ordinating body temperature. Every 24 hours, your body temperature cycles from high to low, varying by as much as one degree.

When it is time to wake up and be active, your body temperature rises slightly and when it is time to fall asleep it drops a little and again it is your body clock that regulates that temperature difference.

Another vital element in sleep regulation is the hormone Cortisol, which is the body’s chief stress fighting hormone.

We have very high cortisol levels when we are in ‘fight or flight’ mode, but they normally drop dramatically at night as we relax and prepare for sleep.

As with body temperature, the natural rise and fall of cortisol in the body must continue on it’s usual course throughout every 24 hours.

However, if you are constantly stressed then this cycle is disrupted and it becomes very difficult to get a proper restful night’s sleep.

Noradrenalin is responsible for setting the energy levels in the body, and is related to adrenalin. Noradrenalin is one of the positive messengers and is vital to a healthy nervous system. If levels of noradrenalin drop, we don’t have enough energy and feel tired and exhausted, with no enthusiasm to do anything. If you feel constantly exhausted and lethargic when stressed, it may be that your level of noradrenalin that is out of balance.

Dopamine is the third positive brain messenger and is responsible for both our pleasurable and painful feelings. We produce natural morphine-like molecules in our brains that are known as endorphins and they regulate our awareness of both pain and pleasure. Dopamine is found in the area of the brain next to where endorphins are released so if our dopamine messengers fail then our production of endorphins is also threatened.

It is stress that causes dopamine failure and if you notice that you are more sensitive to pain than usual that could be a signal that your dopamine messengers are not functioning fully. Dopamine is also responsible for the area of your brain that allows you to enjoy life. When stress interferes with dopamine function the pleasurable messages are no longer being transmitted and things that normally you find enjoyable become dull and uninteresting to you.

So we can see that when life is running according to plan the positive messages are able to keep up with our needs, but when we are under stress it appears that too many demands are placed on the positive messengers and their ability to keep up with the flow of messages to other cells seems to slow down.

If the stress continues, then the positive messages begin to fail. If this happens, then the important nerve centres receive more negative than positive messages and a state of brain chemical imbalance is present. This shift over to more negative than positive brain messengers being sent can result in a sense of being overwhelmed by life, anxious and unable to cope.

A common complaint in this situation is a lack of energy and enjoyment of life and often great problems in sleeping.

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