The hidden reason you’re always tired, struggling with brain fog and lack of motivation… and how to beat it, by GP and emergency medicine expert DR JOSE CRESPO

Daily Mail journalists select and curate the products featured on our site. If you make a purchase through links on this page we will earn a commission – learn more

There is a silent epidemic affecting millions of people and most have no idea it is happening.

It begins with a basic survival response inside the body.

When you are injured or infected, your immune system emits a wave of chemical signals that summon white blood cells to the scene. Blood vessels dilate, fluid leaks into the tissue, and the area becomes warm, swollen, and red.

This is inflammation; It is the body’s way of containing damage, combating threats, and initiating the repair process. It is a life-saving response in the short term.

However, in modern life, this system can become overactive. Instead of shutting down after the threat has passed, it may remain open at a low level for months or even years.

This is known as chronic, low-grade inflammation, and experts believe it is now common in industrialized societies. You don’t feel it directly. But you feel what it does to you.

From fatigue and confusion to low mood and lack of motivation, this hidden biological process may be silently shaping how your body and mind function every day.

According to GP and emergency medicine physician Dr Jose Crespo, the condition not only affects long-term health, but can also affect your ability to think clearly, sustain your energy and follow through on your goals. Here are five key ways that are holding you back and what you can do about them.

Why do you feel more tired than you should?

If you find yourself tiring more easily than before (during exercise or just getting through the day), inflammation may be playing a role.

Over time, chronic inflammation damages the inner lining of blood vessels, making them less flexible and less efficient at regulating blood flow. This reduces how effectively oxygen and nutrients are distributed throughout the body.

The result is a slight but significant decrease in physical efficiency. Muscles may fatigue more quickly, recovery may take longer, and overall endurance begins to decline.

Even before any diagnosable conditions arise, this reduced circulation can leave you feeling constantly exhausted, as if your body is working harder than it should for the same output.

Why does your brain feel fuzzy and unfocused?

This feeling of brain fog (having trouble concentrating, forgetting things more easily, or having trouble thinking clearly) may have a biological explanation.

Inflammatory chemicals released into the bloodstream can travel to the brain and affect how nerve cells communicate. This impairment affects basic processes related to memory, focus and decision-making.

Studies have shown that even mild, short-term inflammation can impair memory and concentration within a few hours. Over time, higher levels of inflammation were also associated with decreased brain volume and poorer performance on tasks requiring planning and attention.

Dr Jose Crespo, author of The Science of Being

In other words, inflammation doesn’t just affect the body; It can also directly affect how clearly you can think.

Why might your mood drop for no obvious reason?

Low mood or anxiety is not always purely psychological. In some cases, it can be caused in part by what’s going on in the body.

Inflammation affects how the body processes tryptophan, an important building block needed to produce serotonin, which helps regulate mood. As inflammation increases, serotonin production may decrease, while other byproducts that can negatively affect brain cells may increase.

This change can trigger symptoms similar to those seen in depression and anxiety; these include low mood, irritability, and feelings of emotional dullness.

For some people, this may help explain why they constantly feel down or anxious without an obvious external cause. Inflammation is unlikely to be the only factor, but it may be an important and often overlooked factor.

Why does your energy never fully return?

If you feel like your energy never fully recovers, even after rest, inflammation may be keeping your body under constant tension.

During inflammation, the body diverts resources to immune activity rather than performance, repair, and growth. It effectively goes into protective mode, prioritizing defense over efficiency.

At the cellular level, inflammatory signals can also interfere with mitochondria, structures responsible for energy production. This can contribute to fatigue by reducing the amount of usable energy your cells produce.

Inflammation is also linked to decreased motivation to engage in effortful tasks; This suggests that feelings of low energy may partly reflect a lack of biological energy rather than simple fatigue.

Why do you have a hard time sticking to good habits?

If you’re having trouble sticking to routines or following good intentions, inflammation may be affecting the part of the brain responsible for self-control.

Inflammatory chemicals can reduce activity in the prefrontal cortex, the region involved in planning, decision-making, and regulating behavior. This makes it difficult to focus, resist distractions, and maintain discipline over time.

Research also suggests that inflammation can also impair working memory and attention, which are essential for forming and maintaining habits.

In practical terms, this means that what feels like a lack of willpower may not just be a personal failure. In some cases, it may reflect an underlying biological condition that makes self-regulation more difficult.

An example of this is a forty-two-year-old manager named Arthur, who had difficulty staying productive despite trying multiple strategies. Tests revealed high levels of inflammation. After improving his sleep, cutting out processed foods, and adjusting his diet, his mental clarity improved and the same strategies began to work.

His difficulties were due to physiology rather than lack of discipline.