Everything you need to know about cortisol

Cortisol is not just a stress hormone, it also helps regulate blood sugar and control the body’s use of fats, proteins, and carbs. However, when levels are persistently raised, problems can arise

Cortisol one of many hormones that help regulate how the body responds to stress Picture: iStock 

It is known as the stress hormone and often blamed for causing a long list of side effects. Social media will tell you that cortisol imbalances are linked to visible signs of ageing, anxiety, bloating, weight gain, joint pain, and insomnia. But how much of this is true, and do we really need to worry about having too much cortisol?

In healthy people, cortisol levels spike and drop throughout the day. It is often wrongly blamed for causing stress. In reality, it is one of many hormones that help regulate how the body responds to stress, and it is not solely responsible for the many effects associated with chronic stress.

But it is much more than just ‘a stress hormone’, says the neuroscientist Dr Sabina Brennan, an adjunct assistant professor at Trinity College Dublin and author of Brain Fog. “Cortisol is indeed involved in the stress response, but it has many other roles,” she says. “It controls your body’s use of fats, proteins, and carbs, suppresses harmful inflammation, regulates blood sugar, and increases blood sugar.”

When levels of cortisol are persistently raised, however, problems can occur. “In normal situations, the body’s stress response allows hormone levels to return to optimal conditions when the stressor has gone,” Brennan says. “But prolonged or poorly managed stress can negatively impact health, affecting your brain and the way it functions.”

Chronically high cortisol disrupts sleep, hampers the immune system, and causes disruptions to blood sugar and blood pressure control. So, how do we know when our cortisol levels are too far off kilter? Here, we get the lowdown:

Are all cortisol spikes bad for us?

Cortisol starts being secreted in the morning and, even in healthy people, can rise during the day to keep you energised before falling again in the evening when sleep hormones like melatonin take over.

“We need this cortisol awakening response (CAR) first thing to give us the get-up-and-go to get out of bed and face the demands of the day,” says Dr Jenna Macchiochi, an immunologist and author of Immune to Age. “But the morning cortisol spike is hugely influential in other aspects of our overall health.”

It helps the thymus gland to quality check immune cells, prompting the destruction of reactive T-cells that can be problematic and “acts like water to the inflammatory fire” that can build in the body. It is only when cortisol levels are raised long-term that it can become problematic. Chronic stress makes the brain less sensitive to cortisol, so that it stops sending the signal for it to be switched off.

How can we test it — and what should we look for?

Cortisol testing kits that use a finger-prick cortisol blood test are widely available online — check those by Get Tested (€69; gettested.ie) or Dr Clinic (€99; drclinic.ie). You can also book in-clinic stress blood tests at various locations of The Health Lab (€75; thehealthlab.ie) or Pure Pharmacy (€69; purepharmacy.ie).

Normal early morning blood cortisol ranges typically fall between 150-300 nanomoles (nMol) per litre. Anything significantly over 300 is likely getting too high, and levels over 1000 nMol/L are concerning, so you should speak to a GP if in the more extreme ranges.

If doctors are concerned that an underlying problem with your adrenal gland function is causing extreme irregularities in cortisol production, you will be referred for tests.

Relatively rare conditions include Addison’s disease, which affects one in 14,000 people in Ireland and is caused by too little cortisol, or Cushing’s syndrome, which is caused by too much cortisol and affects about one person in a million.

For the rest of us, there is no biological need to keep tabs on cortisol levels if generally healthy, but if you do decide to track them, you will need to do it every three to four months for an accurate insight. Since levels of the hormone spike first thing when we wake up, it is best to test in the morning.

Is cortisol to blame for so-called ‘meno belly’?

A cocktail of hormones contributes to body changes in the menopause, and cortisol is often one of them. Oestrogen plays an important role in cortisol regulation, and when levels start to drop during the menopause, cortisol levels rise in response. If this continues for several months, it can cause chronically heightened cortisol levels, which impact fat and carbohydrate metabolism and encourage the body to hold fat around the middle. A drop in muscle-building human growth hormone (HGH) and DHEA, and a rise in a weaker oestrogen called estrone (or E1) that is produced in fat tissue, create the perfect hormonal conditions for midsection weight gain.

Will too little sleep send my cortisol levels into overdrive?

In her book, It’s Probably Your Hormones, Dr Mary Ryan, consultant endocrinologist at Bon Secours hospitals, describes how healthy cortisol follows a daily rhythm and that poor sleep and irregular routines disrupt the process. During sleep, the sympathetic nervous system slows, and cortisol levels are reduced.

“With poor sleep the stress response can continue at daytime levels,” says Macchiochi. “If we wake stressed, we feel tired, and our immunity becomes dampened as the cycle through more stress and less sleep cycles continues.”

If you are trying to lose weight when not sleeping well, you will be holding on to what you want to lose — surplus weight. “When you get too little sleep for long periods, cortisol levels increase and your body goes into fight or flight ‘stress’ mode more easily,” says the nutritionist Rhiannon Lambert, author of The Science of Nutrition. “In response, your body also becomes reluctant to give up fat, preferring to hold onto it as a rich energy source in case it is needed for self-protection.”

Do you have cortisol face?

Believe what you read on social media, and a puffy face is a clear sign of raised stress hormones, hence the name: “cortisol face”. It is true that some medical conditions in which the adrenal glands make too little or too much cortisol can cause facial puffiness. In the rare cases of Cushing’s syndrome, for example, elevated cortisol drives central fat redistribution and fluid retention, producing a characteristic rounded, puffy facial appearance.

What’s less certain, say experts, is whether the kind of chronic, low-grade cortisol elevation many of us experience from modern life, overexercising or poor sleep produces any facial changes. If you wake with a puffier face, it’s more likely to be a sluggish lymphatic system and fluid retention, not cortisol-related.