London - Colour has a significant psychological impact on our everyday lives - affecting our health for better or for worse.
The colour of medication can affect how effective we think it is and, if a hospital consultation room is painted a warm, neutral colour, patients are more likely to feel at ease.
It can also affect children and their ability to learn and be happy, according to a new initiative at Overdale Infant School in Knighton, Leicester.
In September, the school announced it was banishing gaudily hued chairs, walls and decor, and replacing them with furniture in brown and beige and hessian-fabric wallpapers.
Staff have already revamped four of the 12 classrooms, and plan to change the decor in the remaining eight.
The theory is that, while brightly coloured toys and decor can be distracting and over-stimulating for young brains, grey and beige encourage calmness and improve children’s conduct, listening, attention and creativity.
Doctors have been aware of the impact colour has on our health for decades. Back in 1996, an analysis in The British Medical Journal (BMJ) of 12 studies suggested that the colour of drugs can actually alter their effectiveness in patients.
Epidemiologists at the University of Amsterdam found that people often associate red, yellow and orange tablets with the type of stimulant effects found in medications such Ritalin, used in the treatment of ADHD, and the narcolepsy drug Adderall.
Meanwhile, patients associate blue and green tablets with tranquillising effects, as produced by medications such as SSRI (selective serotonin re-uptake inhibitor) antidepressants, as well as benzodiazepine sedatives.
Researchers found that when the colour matched the drug’s expected effects, it worked significantly better in patients.
Conversely, when the colour of the medication clashed with expectations, the drug was not as effective as it had been in trials that used colour-free tablets.
Something similarly disruptive may happen when the colour of a patient’s drug is unexpectedly altered, according to another study in The BMJ, published in 2013 by specialists at Brigham and Women’s Hospital in Boston, Massachusetts, in the US.
The study monitored more than 61 000 patients with epilepsy for five years and found that, when the colour of their prescription pills was changed, they became up to 27 percent more likely to stop taking them, raising their risk of a dangerous seizure.
Epilepsy medication is particularly problematic in terms of its colour because generic types of the same drug come in a wide range of hues.
For example, one epilepsy drug, extended-release carbamazepine, comes in eight colours, ranging from pink to blue-green, the US researchers noted.
"Pill appearance has long been suspected to be linked to medication adherence, yet this is the first empirical analysis that we know of that directly links the physical characteristics of pills to patients’ adherence behaviour," said the lead researcher Dr Aaron Kesselheim, a professor of medicine.
Patients come to trust a particular colour of pill, the researchers concluded, and when it changes, they often worry that the pill is less effective or more dangerous.
But it’s not just the colour of the medication that impacts on our health. The colour of rooms where healthcare is delivered can also alter our perception of medical care - and aid recovery.