top of page

The biology of stress


✨This is a HUGE topic, so I'll start with the basics of how stress works, then discuss more in future posts

✨We all know about stress, but how exactly does it work?

✨A basic description is that when our amygdala (the 'alarm system' part of brain) detects any threat, it sends signals to another part of our brain, the hypothalamus

✨This triggers the hypothalamus to release a flood of hormones and chemicals, including adrenaline, cortisol, and inflammatory cytokines

✨Adrenaline is the 'fight or flight' hormone, that gets our body ready for action.


👉increases blood pressure and heart rate,

👉increases blood flow to the brain and muscles

👉 diverts all our energy into getting ready to run or fight

✨It also:

👉diverts blood away from the reproductive organs and gut,

👉shuts down the 'rational' part of our brain

✨Cortisol is the 'stress' hormone, which helps us respond to acute stress


👉 increases blood sugar (to provide fuel)

👉 suppresses immune system (ie shuts down all non urgent processes)

✨This explains all the symptoms we usually get when feeling stressed

👉racing heart

👉fast shallow breathing

👉butterflies in the stomach/poor digestion

👉 inability to think clearly

It also reduces ability to reproduce/shuts down libido, and suppresses immune function

✨Short term stress is good (it helps us survive in emergencies)... The issue is that low grade chronic stress is NOT

✨Longterm stress results in chronically raised levels of adrenaline and cortisol, causing all the symptoms above, as well as fatigue, weight gain, raised blood sugar levels, and even altered sex hormones

✨Cortisol and sex hormones (oestrogen, testosterone etc) both use the same precursors (cholesterol) - if the body is constantly producing cortisol, it can impact on other hormone levels

✨Fatigue, mood swings, hormonal symptoms, and sleep issues are common symptoms of chronic stress

✨It's estimated that up to 80% of visits to GPs are for stress related symptoms or conditions!!

✨The great news though, is that there are many effective simple ways to reduce stress - watch this space!!

3 views0 comments

Recent Posts

See All


bottom of page