Have you ever wondered how your brain tells you when you are feeling hungry or full up; or tired or the reason you felt happy after eating that delicious ice-cream1?
Many of the functions of our brain and central nervous system operate at an unconscious level and are mediated by biochemical influences such as hormones.
Have you ever thought about what you might do if you were on holiday in Canada and a big brown bear approached you in the woods?
Your brain wouldn’t really give you much to time to think about it as it would be instantly preparing you for either one of two things – fight or flight. You would either fight the bear (if you were brave enough) or flee from the bear and run for your life. This response is controlled by the sympathetic nervous system (SNS) which is part of the autonomic nervous system. During this response, the SNS sends out impulses to your smooth muscles and glands, causing the adrenal medulla to release stress hormones into the bloodstream. These stress hormones include epinephrine (adrenaline) and norepinephrine (noradrenaline) and are responsible for several bodily changes in the body, including increases in your heart rate and blood pressure, a widening of the airways in your lungs, your pupils will dilate so more light can enter the eye, your blood-glucose levels will increase, you’ll get goose-bumps as result of both adrenaline and glucose in your muscles, non-essential functions such as your digestion and immune systems will shut down, and your brain will be fully focused on the threatening situation in front of you.
The fact is hormones can act as neuromodulators and play critical roles influencing our growth, stress response, mood and sleep. For example, the pineal gland which is positioned near the centre of the brain also referred to as the “third eye”. This gland produces a hormone called melatonin which helps to regulate the human sleep-wake cycle known as the circadian rhythm. If you have low melatonin levels you may have sleep disturbances, and be irritable and tired during the day.
Another important chemical in your brain is dopamine. Earlier, you were asked if you knew why you felt happy after eating a delicious ice cream. That feeling of happiness is all down to a chemical in your brain called dopamine, often referred to as the happiness chemical. Also linked to happiness and well-being are endorphins, serotonin and oxytocin, which are often released after exercising. Dopamine affects your movements, your mental alertness, and sensations of pleasure and pain. Dopamine neurotransmitters are located in the deep middle region of your brain called the substantia nigra and ventral tegmental area. The production of dopamine is reliant on a dietary intake of omega-3 fatty acids. Studies have persistently shown that a lack of these omega-3 highly unsaturated fatty acids reduces the amount of dopamine available in your brain.
Dopamine plays a critical role in the way our brain responds to reward and is produced after most pleasurable acts such as eating your favourite meal or winning a race. Alterations in dopamine or a reduction in dopamine levels will affect the way you respond to reward and will demotivate you. You may also become forgetful, irritable, experience mood swings, fail to complete tasks, become depressed, lack concentration, develop ADHD-type symptoms and suffer with fatigue.
Eating oily fish and seafood at least twice a week will help ensure an adequate intake of omega-3 optimising the production of dopamine.