Fatigue

Fatigue is a normal and important signal from the body. It indicates that energy has been used and that recovery is needed. Everyone feels tired from time to time, for example after a busy workday, an intense training session, or a period of little sleep. In such situations, fatigue is actually functional: it helps you take rest and gives the body a chance to recover.

It becomes a problem when fatigue persists or no longer goes away well after rest. In that case we speak of overtiredness. This is becoming more and more common and has a major impact on daily functioning. Fatigue can be both physical and mental. Sometimes the fatigue is short-lived and sometimes it is present for a long time.

How fatigue works

To understand why we get tired, it is important to know how the body handles energy. Almost everything we do requires energy: not only moving, but also thinking, the functioning of organs, and maintaining the body itself. We get this energy from nutrients such as carbohydrates, fats, and proteins, which are converted into fuel for our cells.

During the day part of that energy supply is depleted and processes in the brain change. For example, the amount of adenosine increases, a substance that strengthens the feeling of sleepiness. At the same time, melatonin plays a role in the sleep-wake rhythm: this hormone makes us sleepy in the evening. During sleep these processes are "reset" and energy stores are replenished.

When the body is subjected to extra load, for example due to intensive exercise, illness, or prolonged stress, more time is also needed to recover. If that recovery time is lacking, fatigue accumulates.

Physical and mental fatigue

Physical fatigue arises after physical exertion. Think of sports, heavy work, or a long day of activity. The muscles have then used energy and small changes occur in the muscle tissue. This is a normal reaction of the body. It usually recovers on its own within hours to days.

Mental fatigue feels different. It mainly arises from prolonged concentration, stress, or a high cognitive load, such as during a busy workday with lots of stimuli. Strikingly, you can feel tired then even if your body has not been heavily physically loaded. The exact cause is complex, but it has to do, among other things, with changes in the brain and reduced efficiency of mental processes during prolonged effort.

What many people notice is that being active actually helps with mental fatigue. A walk or bike ride clears your head. This is because blood flow to the brain improves and substances are released that positively influence energy levels and mood.

Short-term and long-term fatigue

After a day of exertion it is normal to feel tired. This short-term fatigue usually disappears after a good night of sleep. During sleep, the body recovers, energy stores are replenished, and important processes in the brain and muscles are regulated.

Sometimes, however, fatigue remains present even after sufficient rest. If this lasts longer than a few months, we speak of long-term or chronic fatigue. The body then no longer seems able to recover properly. This can have various causes, such as persistent stress, sleep problems, illness, poor nutrition, or a prolonged imbalance between load and recovery. Often both physical and mental factors play a role.

Fatigue, illness, and stress

Fatigue is a common symptom of illness. When the body has to fight an infection or another condition, that costs a lot of energy and causes tiredness. This is seen, for example, with the flu, but also with conditions such as diabetes, anemia, or thyroid problems.

Stress also plays a major role. In an acute situation, stress is useful: the body prepares to act and to mobilize energy. But when stress is present for a long time, the body remains in an 'on mode'. That constantly uses energy and impedes recovery. This can eventually lead to chronic fatigue.

Recovery: the key to less fatigue

To reduce fatigue, recovery is essential. Sleep plays the biggest role in this. During sleep, the body has the chance to replenish energy and recover from the load of the day. But recovery is broader than sleep alone.

Relaxation during the day is also important. This does not necessarily mean doing nothing, but engaging in activities that cost little energy or actually give energy, such as walking, reading, or spending time with others. In addition, regular physical activity helps the body function well. Exercise stimulates blood flow and supports recovery, as long as there remains sufficient balance with rest.

What can you do about fatigue?

With fatigue it is especially important to look at the balance between what costs energy and what provides energy. A regular sleep rhythm, healthy nutrition, and sufficient physical activity are the foundation. Even though it sometimes feels counterintuitive, light activity often helps you feel more energetic.

When fatigue persists and does not improve, it is wise to consult your family doctor. Sometimes additional testing is needed to rule out physical causes, such as vitamin or mineral deficiencies or other medical problems.