Five widely accepted means of improving our physical health are:

  • Not smoking
  • Eating healthily
  • Exercising
  • Limiting alcohol consumption
  • Getting enough sleep

Here we consider if research suggests these may also help improve our mental health – and if they may possibly reduce the risk of mental illness.


People with mental illness are more likely to smoke. They often believe smoking helps with depression, anxiety and stress. However, research suggests the opposite i.e. that quitting smoking is associated with significant decreases in anxiety, depression and stress, when compared with continuing to smoke.1

It isn’t yet clear whether smoking causes or is a result of mental conditions. However, some researchers believe that smoking could act as a trigger for mental ill-health.2

Eating healthily

A study of more than 10,000 initially healthy Spaniards found that those who followed a Mediterranean diet (rich in vegetables, fruits, nuts, whole grain and fish) were 30% less likely to develop depression during the next four years.3 A number of studies have suggested that the Mediterranean Diet may be good for the brain more generally, being also associated with a slower rate of cognitive decline and a lower risk of developing Alzheimer’s Disease.4

If a healthy diet might protect against mental illness, does an unhealthy diet increase the risk? That was the verdict from a study of 23,020 Norwegian women and children, which suggested that children who are exposed to ‘junk food’ while their mothers are pregnant and during early childhood are at increased risk of developing mental health problems, such as anxiety and depression.5

This potential link between diet and mental health has led to the development of Nutritional Psychiatry.6 A 2017 review of the evidence noted, ‘Consistent epidemiological evidence, particularly for depression, suggests an association between measures of diet quality and mental health, across multiple populations and age groups; these do not appear to be explained by other demographic, lifestyle factors or reverse causality.’7

One developing area of research is the human gut microbiome, with what we eat having a significant influence on our gut health (and potentially therefore, through what has been described as the gut-brain axis, on our mental health). It has even been suggested that conditions such as schizophrenia and bipolar disorder8 and autism9 may be associated with an altered gut microbiome – although much more research is needed here before we a definite conclusion can be reached.


A study that followed nearly 34,000 adults for 11 years concluded that regular leisure-time exercise of any intensity provides a degree of protection against future depression (but not anxiety).10 

This is in line with a range of studies that suggest exercise can also be helpful when treating depression11 - although the effect may not always be significant and there may be little or no effect when treating major depression.12


The Royal College of Psychiatrists advises that heavy, long term alcohol consumption can lead to psychosis - hearing voices when there is nobody there; and dementia - memory loss, rather like Alzheimer's dementia. 

It also notes there is a connection between depression and alcohol, for example with self-harm and suicide much more common in people with alcohol problems. It seems that it can work in two ways:

• you regularly drink too much (including ‘binge drinking’) which makes you feel depressed OR
• you drink to relieve anxiety or depression.

Either way, alcohol can affect the chemistry of the brain, increasing the risk of depression.13


A 2017 study with 204 college students aged 18-25 suggested that regular sleep is important for wellbeing, with higher sleep regularity significantly related to higher morning and evening happiness, healthiness and calmness during the week.14 This is in line with research into the effects of sleep deprivation. A 2017 review  of the evidence concluded that in otherwise healthy adults, the short-term consequences of sleep disruption include increased stress responsivity, somatic pain, reduced quality of life, emotional distress and mood disorders, and cognitive, memory, and performance deficits.15

A Note of Caution

Research into the influence on mental health of factors like diet, exercise and smoking is still in its infancy and some of the research has not always been of the highest quality. Also, the research has often identified an association between these factors and mental health. An association between two factors doesn’t automatically mean that one causes the other, so more research is needed into whether there is a cause and effect relationship here – but, given the association, this is an area worth researching further.

It is also worth noting that many different factors,16 and the inter-relationship between them, can trigger mental health problems. Smoking, heavy alcohol consumption, unhealthy diet and lack of exercise are just some of the many potential factors. However, they are factors we can potentially control, hence the value of considering them.


  • People with mental conditions are more likely to smoke – although whether smoking can help trigger mental conditions is still being researched.
  • A healthy diet appears to reduce the risk of mental illness, particularly depression, and possibly (through improved gut health) also the risk of schizophrenia, bipolar disorder and autism.
  • Regular leisure time exercise also appears to reduce the risk of depression – although research into whether it can help treat depression has produced conflicting results.
  • There is a connection between alcohol and depression and very heavy long-term alcohol consumption can lead to psychosis and dementia.
  • Getting enough regular sleep is importanty for helping maintain wellbeing.
  • More good quality, large-scale research is needed, particularly where associations have been identified but not yet a clear cause and effect.
  • In the meantime, not smoking, exercising regularly, healthy eating, limiting alcohol consumption and getting enough regular sleep are all factors we can control. They are all proven to be good for our physical health – and may also be good for our mental health too.

Michael Baber September 2018



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2. Smoking and Mental Health. ASH (Action on Smoking and Health) Fact Sheet. Available online at:

3. Ash M. A Nutritional Proposal For Improving “Mental health” with a focus on depression. Clinical Education. 2012. Available online at:

4. Medina J L, Jacquart J, Smits JA. Optimizing the Exercise Prescription for Depression: The Search for Biomarkers of Response. Current opinion in psychology 4. 2015: 43–47.

5. Pedersen T. In Young Kids, Junk Food Linked to Mental Illness. Psych Central. Available online at:

6. International Society for Nutritional Psychiatry Research.

7. Marx W, Moseley G, Berk M et al. Nutritional psychiatry: the present state of the evidence. Proc Nutr Soc. 2017 Nov;76(4):427-436.

8. Dickerson F, Severance E, Yolken R. The Microbiome, Immunity, and Schizophrenia and Bipolar Disorder. Brain, behavior, and immunity 62 (2017): 46–52.

9. Kelly J R, Minuto C, Cryan JF et al. Cross Talk: The Microbiota and Neurodevelopmental Disorders. Frontiers in Neuroscience 11 (2017): 490.

10. Harvey SB, Overland S, Hatch SL et al. Exercise and the Prevention of Depression: Results of the Hunt Cohort Study. The American Journal of Psychiatry. 2017. Available online at:

11. Kyam S, Kleppe CL, Nordhus IH et al. Exercise as a treatment for depression: A meta-analysis Journal of Affective Disorders. 2016 Volume 202, Pages 67–86 

12. Krogh J, Hjorthoj C, Speyer H. Exercise for patients with major depression: a systematic review with meta-analysis and trial sequential analysis. BMJ Open. 2017. Available at: 

13. Alcohol and Depression. Royal College of Psychiatrists Public Engagement Editorial Board. 2015. Available online at:

14. American Academy of Sleep Medicine. "Sleep regularity is important for the happiness and well-being of college students: Study shows the importance of regular sleep patterns." ScienceDaily. 5 June 2017. Available online at

15. Medic G, Wille M, Hemels MEH. Short and long term health consequences of sleep disruption. Nat Sci Sleep  2017; 9: 151–161


16. Mental health problems – an introduction. Mind. Available online at: