If you want to discover how your body is ageing on the inside, look no further than your immune system. The thymus gland, situated in front of your chest just above your heart, plays a vital role in immunity. For some reason, the thymus starts to shrink very early in life, rendering it less capable of stimulating and preparing immune cells.

While the precise reasons for this remain obscure, what we do know is there’s a host of factors that dilute and weaken the function of the thymus while others enhance thymus function. In turn, the health of the immune system is linked inexorably to the state of your hormonal system. So let’s look at some of the key hormones that impact on immunity and the thymus.

Cortisol

This is known as the stress hormone because it modulates the way stress affects your body. Cortisol is produced by your adrenal glands, situated just above your kidneys, and it’s the hormone responsible for getting you out of bed in the morning. Without cortisol, you will become fatigued and find it difficult to meet the challenges of the day with enthusiasm. Irritability and anxiety, light-headedness when you stand up, an inability to think clearly and craving for sweet foods are typical of a cortisol deficiency.

You need a certain amount of cortisol to boost your immune system, but the production of excessive amounts can weaken immune function and cause the thymus to shrink. The production of excessive amounts of cortisol can make it difficult for you to get a good night’s rest and will cause you to wake up at all hours of the night. You’ll also find it harder to lose weight and you’ll notice you are bruising easily. Large amounts of cortisol make it harder for some immune cells to multiply.

A good way to evaluate your cortisol levels is through a urine test that assesses your body’s production of cortisol over a 24-hour period. Another way is to do a saliva hormone profile, which involves the collection of saliva at different times of the day to give you a sense of how your body is manufacturing cortisol.

Ideally, your production of cortisol should achieve a high in the early morning, the time your body needs to gear up for activity. From then it should gradually go into decline during the day so that, by nightfall, the production of this hormone should have dissipated, allowing a restful night. So a salivary assay can establish whether your body is overproducing cortisol at night.

If your cortisol production peaks at night instead of the morning, this obstructs the beneficial function of growth hormone and melatonin, both of which are good for your immune system. It will also make it more difficult for you to sleep properly with so much cortisol charging your brain. Too much cortisol also gets in the way of the production of another hormone from the adrenal glands, dehydroepiandrosterone, also known as DHEA.

DHEA

In many ways DHEA can be viewed as the anti-stress hormone. While cortisol prevents T-cells from multiplying, DHEA increases immune cell levels and prevents cortisol from causing the thymus to shrink. Unfortunately, as you age your body produces less DHEA, while some reports indicate cortisol’s production and its adverse effect on the immune system increase with ageing. One way you can encourage your body to produce more DHEA is to meditate regularly.