Stress and the nervous system

Always ‘on’? How stress affects your body

You lie in bed at night, but your mind keeps racing. Your shoulders are tense, you sleep fitfully, and even at the weekend you find it hard to unwind.

Sound familiar? Your body may be staying in fight-or-flight mode for longer than is good for you.

Our bodies are designed to alternate between exertion and recovery. Your stress system is meant to kick in when you’re under real pressure: a deadline, a difficult conversation, a packed day. Afterwards, your body normally switches back to rest on its own. But when that balance is missing for a long time, your system stays stuck in action mode [1].

How exactly does it work, and what can you do about it?

The autonomic nervous system: two modes

Your nervous system consists broadly of two parts. The somatic nervous system controls conscious movements, such as walking or picking something up. The autonomic nervous system works largely unconsciously, regulating vital functions such as your heart rate, blood pressure, breathing, body temperature and digestion.

The autonomic nervous system has two modes:

• The fight-or-flight response (the sympathetic nervous system) prepares your body for action or danger.
• The rest mode (the parasympathetic nervous system) supports recovery, rest and digestion: the rest-and-digest response.

What happens when you’re stressed?

When your brain perceives a situation as threatening or stressful, it switches into action mode. Stress hormones are released, such as adrenaline, noradrenaline and later cortisol [2]. This response evolved to prepare you quickly for action. Handy when there’s a tiger right in front of you.

When stress persists, your fight-or-flight response stays active for too long, leaving too little room for your rest-and-digest system to help your body recover. This can even happen after the source of stress has passed [1, 2].

What can you expect?

Ongoing stress can show up in many ways [3].

In your mind

• Feeling constantly on alert, unable to relax
• Difficulty concentrating and forgetfulness
• Difficulty making decisions
• Worrying and restlessness

How you feel

• Irritability
• Anxiety
• Reacting more emotionally
• Feeling overwhelmed or powerless
• Reduced resilience

In your body

• A higher heart rate and blood pressure
• Faster breathing
• Muscle tension, especially in the neck, shoulders and jaw
• Digestive problems: bloating, cramps, constipation or diarrhoea
• Fatigue and sleep problems
• Reduced immunity

Two examples of how this works

High blood pressure

When you’re stressed, adrenaline and noradrenaline make your heart pump faster and harder. At the same time, blood vessels in different parts of your body narrow, causing your blood pressure to rise. With prolonged stress, cortisol can also play a part, including by making blood vessels more sensitive to stress hormones and affecting fluid and salt balance. In the long term, chronic stress is associated with a higher risk of high blood pressure and cardiovascular disease [4].

Struggling to lose weight

Chronic stress can make weight loss more difficult in several ways [5]:

1. Increased appetite: cortisol stimulates your appetite, especially for foods high in sugar and fat. From an evolutionary perspective, this was useful for replenishing your energy reserves after a threat.
2. More abdominal fat: cortisol promotes fat storage, especially around the abdomen. This fat is metabolically active and is associated with a higher risk of type 2 diabetes and cardiovascular disease.
3. Disrupted satiety: prolonged stress can affect the hormones that regulate hunger and fullness, such as leptin and ghrelin. This can make it harder to regulate your appetite and weight.
4. Indirect effects: stress often goes hand in hand with poor sleep, less exercise and emotional eating. These can also make losing weight harder.

Get your nervous system back in balance

There are many ways to help your body switch back into rest mode. What works for one person may not work as well for another. It’s a matter of finding what works for you.

Start by becoming more aware. Notice when you keep going automatically without taking a break. Every now and then, take a minute to check in: how is my mind, how does my body feel?

Schedule small breaks to recharge. A short walk, a one-minute breathing exercise, looking outside for a moment, or having a cup of tea without distractions can help your nervous system unwind. Breathing exercises are now supported by good research: a review of randomised studies found that they can reduce stress [6].

Don’t confuse relaxation with recovery. Watching TV, gaming or scrolling may feel relaxing, but your brain is still processing stimuli: images, sounds and a constant stream of information. As a result, your nervous system stays slightly switched on. That doesn’t make these activities bad, and they can be enjoyable. But to truly recharge, your body needs something else: rest without constant stimulation.

Choose real rest. Try walking without a destination, listening to calm music, taking a yin or restorative yoga class, or practising yoga nidra (sleep yoga). At these times, your brain has less to process, allowing your stress system to truly wind down.

Consistency beats perfection. Your nervous system adapts through repeated experiences of calm and recovery. A five-minute daily breathing exercise is likely to have more impact than a long session now and then.

Would you like to try yoga nidra? Click here for a yoga nidra session (duration: 17 min)

Would you like to learn how to help your body relax again?

Learn more about [Stress, anxiety and sleep] and the programme The Breathing Space, or book a free 15-minute introductory call.