Stress - a hidden cause of poor immunity
Does stress affect immunity?
Many people may notice when they are tired and stressed, they seem to get sick more often, or take longer to recover from infections
And while diet, exercise, sleep and hygiene can all make a difference, stress is an area that's not discussed much - despite the fact it has a huge effect on our immune system!
When we are under stress:
✔️Our sympathetic (fight or flight) nervous system communicates directly with our immune (lymphatic) tissue via nerve fibres. Even previous stress and trauma can be 'remembered' by our immune system, and is part of why there is such a strong link between stress and conditions like autoimmune disease and allergies. Our fight or flight nervous system releases hormones such as adrenaline and cortisol
✔️Cortisol (our stress hormone) impacts on immunity, by altering our immune response and white blood cells. Short term this helps by suppressing inflammation (as part of the fight or flight reflex), to help us function under threat
✔️Longer term though, stress works differently - chronic stress results in lower levels of t cells (white blood cells that are part of the immune response), and also making these t cells less able to respond and fight off infections. Chronic stress also results in elevated levels of chemicals called cytokines, which trigger inflammation and can damage the body
✔️Stress also affects immunity via its impact on our day to day life - when we are stressed, we are more likely to do things that are bad for our immune system (such as eating poorly, not sleeping, not exercising, withdrawing from social contact, and smokimg or drinking alcohol)
Did you know, short and long term stress affect us quite differently though?
Acute stresses (lasting a few minutes or hours) actually help our immunity, by boosting immune cell numbers and activity. This is part of our survival response, as it helps our body cope with threat or injury.
It's also how 'hormetic' stresses such as exercise, fasting, or cold water bathing work - by creating a short controlled stressor that stimulates our immune system.
Chronic stress has a very different effect, by suppressing immunity, and making us more likely to catch infections. This is why infections such as herpes or shingles can reactivate during times of stress
A groundbreaking study of medical students under stress in the 1980s was one of the first to look at this. It found that every year (over a decade), during exam time, the students immune systems became significantly less effective for a short period while they were under stress, with their t cell levels both dropping, and becoming far less able to fight infection. It showed that T cell and NK cell (white blood cell) levels dropped significantly under stress, and the severity correlated with stress levels.
Over 300 studies have looked into stress and immunity since and have found similar effects, especially in older people, or people with depression.
Another great study looked at first year college students, and found the higher their stress levels and the more socially isolated they were, the less they responded to a flu vaccine.
Some other random facts about stress and immunity include:
✔️Loneliness has the same effect as stress on your immune system
✔️Stress can reduce how well you respond to vaccines (develop immunity)
✔️Childhood stress/trauma can affect immunity and inflammation levels well into adulthood, and increase the severity of reactions to infections
✔️Stress can cause viruses to reactivate (a classic example is people getting shingles when stressed - a reactivation of chickenpox)
✔️People caring long-term for unwell family members have been shown to have reduced immunity, are slower to heal from injury, and even have a less effective response to vaccines
✔️Chronic stress is strongly linked with developing autoimmune disease (due to inflammation, as above)
✔️Stress even shortens the ends of your telomeres (DNA), literally making you age faster
The good news is there are many things you can actively do to reduce stress and inflammation, and improve immunity
✔️Regularly connecting with others boosts your immune system and reduces inflammation. Physical contact such as hugs also really help
✔️Excerise is a proven way to reduce cortisol and stress levels, even better if in nature
✔️Activities such as mindfulness, meditation, yoga, conscious relaxation, tai chi etc are all proven ways to reduce stress and therefore improve immunity
✔️Journalling, getting adequate sleep, and laughter can all also help stress and immunity
✔️In another study on medical students, those who were given hypnosis and relaxation training at exam time, had significantly better immune system markers than those who didn't
In practice, most things that help reduce stress levels are likely to improve immunity - the key is finding things that bring you joy, make you feel less stressed, and doing them regularly!
https://www.apa.org/research/action/immune
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4465119/
https://www.simplypsychology.org/stress-immune.html...
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1361287/