Negative thoughts and beliefs


We have a lot more control over our thoughts than many of us realise. This is because thoughts, unlike infections or genetic issues, are self-generated.

Our thoughts are based on several factors, including:

  • Our personality
  • Our experience
  • Our education
  • Our surroundings
  • Our belief systems

How our thoughts can affect our mental health

When thoughts lead to emotions, they trigger chemical reactions, including the release of hormones and neurotransmitters.

The fact that our thoughts impact our physiology is illustrated by the placebo/nocebo effect.

The placebo/nocebo effect

The placebo/nocebo effect is an example of how our thoughts and beliefs, which may or may not be founded on any empirical truth, can lead to feelings which then become our “truth”, impacting our physiology in a very real way.

The placebo effect usually involves positive thoughts which lead to positive physiological changes, whereas the nocebo effect illustrates the detrimental impact our negative thinking can have on our physiology.

According to Joe Dispenza, the placebo effect (and by extension the nocebo effect) involves three stages:

  • Conditioning
    • When we repeat an association enough times it becomes hardwired
    • For example, when we associate a past memory (e.g. taking an aspirin) with a psychological change (getting rid of a headache)
    • When we take a headache-pill-placebo (e.g. a sugar pill), if we believe it’s an aspirin, it will still make us feel better
  • Expectation
    • We associate things outside of ourselves with possible change (e.g. a headache pill, fake or real)
    • Therefore we begin to build up hope and anticipation, and if we feel these emotions strongly enough, our imagination becomes as ‘real’ as reality, because the brain fires the same circuits in expectation of the headache pill, regardless of whether it arrives or not
  •  Meaning
    • We assign intention to an action

We can use the power of the placebo effect for good in our daily lives, because both intention and belief have physical effects.

But also we have to be aware of the negative impact the nocebo effect can have on our health and our lives.

Duhigg, C. (2012). The Power of Habit. London: William Heinemann., Dispenza, J. (2014). You are the Placebo. London: Hay House.

Chronic negative thinking and mental health

Many different situations can contribute to negative thinking, encouraging anxiety and other mental health issues.Greenblatt, J. (2011). Breakthrough Depression Solution. Forest Lake, MN: Sunrise River Pres, p. 16.

  • For instance, we may worry that someone we love is in danger, because they don’t come home when they said they would
  • We wonder what has happened to them, and imagine them being hurt or in danger, which triggers anxiety and the release of stress hormones such as cortisol and adrenaline which can cause further hormone and neurotransmitter imbalances

Or we suffer from disappointed positive thinking, when we expect something positive and it fails to happen, the disappointment that follows can affect us, too.Fiorillo, C.D., Tobler, P.N. and Schultz, W. (2003). ‘Discrete coding of reward probability and uncertainty by dopamine neurons’. Science, 299, pp. 1898–1902.

  • For instance, we may have been told by a psychic that we are about to win the lottery, and as we wait for the lottery results we experience excitement and anticipated joy, which then increases the dopamine levels in our brain
  • When we fail to win, the disappointment causes the level of dopamine to fall, which can contribute to low mood, depression, or a lack of energy

Negative thinking habits

Negative thinking can easily become habitual. If it does, it can operate subconsciously, when we’re busy with other things or even asleep.

This is because these negative thoughts:

  • Use less brain energy than positive thinking, so our brains will tend towards them
  • Forge well-worn pathways in the brain, making such thoughts smoother and more automatic

Repeated negative thoughts, such as anger, resentment, fear, or depression, may cause our bodies to release the stress hormones cortisol and adrenaline. Over time, high levels of these hormones can contribute to mental health symptoms:

Impact of negative thinking on our biochemistry

Chronically high levels of cortisol due to habitual negative thinking can contribute to a range of mental health issues, including:Society of Endocrinology. (2017). ‘Cortisol’. [online] You and Your Hormones. Available at: [accessed 14 Nov. 2017].

Chronically high levels of adrenaline are rare, but they can contribute to mental and physical health issues, including:Society of Endocrinology. (2015). ‘Adrenaline’. [online] You and Your Hormones. Available at: [accessed 14 Nov. 2017].