We often confuse anxiety with fear, believing that we are anxious about something because we are afraid of it.

But are they really the same?

In a family therapy class, Teacher Shen discussed this topic:

A fawn sees a tiger and runs for its life—that's the fear of death.
A fawn doesn't see a tiger yet remains restless—that's death anxiety.

Fear preserves life because it drives us to avoid harm and steer clear of danger. Anxiety, however, drains life, making us uneasy even when all is calm.

Chronic and severe anxiety can further develop into anxiety disorders.

Many anxiety disorders initially manifest as simple "nervous fatigue."

These fatigue symptoms typically progress through muscular, emotional, psychological, and mental stages. If left unchecked, severe mental fatigue can lead to neurosis.

Neurosis, or neurotic disorders, manifests as a decline in mental function, worry, tension, anxiety, depression, fear, compulsions, hypochondria, dissociative symptoms, conversion symptoms, and more.

In short, neurosis encompasses a wide variety of symptoms, but today, we’ll focus on the most common one: anxiety.

Understanding Anxiety Disorders
The clinical term for anxiety disorders is Generalized Anxiety Disorder (GAD). According to the DSM-5 diagnostic criteria, GAD is identified as follows:

Criteria:
A. Excessive anxiety and worry (apprehensive expectation) occurring more days than not for at least six months, concerning a number of events or activities (e.g., work or school performance).
B. The individual finds it difficult to control the worry.
C. The anxiety and worry are associated with three or more of the following six symptoms (with at least some symptoms present more days than not for the past six months):

Restlessness or feeling keyed up or on edge.
Being easily fatigued.
Difficulty concentrating or mind going blank.
Irritability.
Muscle tension.
Sleep disturbance (difficulty falling or staying asleep, or restless, unsatisfying sleep).
D. The anxiety, worry, or physical symptoms cause clinically significant distress or impairment in social, occupational, or other important areas of functioning.
E. The disturbance is not attributable to the physiological effects of a substance (e.g., drug abuse, medication) or another medical condition (e.g., hyperthyroidism).
F. The disturbance is not better explained by another mental disorder.

You can also use the Burns Anxiety Inventory to check if you might have an anxiety disorder.

Let’s start by understanding the four types of nervous fatigue, including muscular fatigue, and how they can progressively develop into anxiety disorders.

1. Muscular Fatigue
Muscular fatigue refers to a decrease in muscle function after prolonged or intense use.

Severe nervous fatigue can lead to prolonged feelings of muscle weakness. Some patients may feel their legs go weak simply from standing.

Beyond fatigue, there is often pain in various body parts: sore calves, abdominal pain, stiff shoulders, and neck discomfort.

Other signs include:

Blurred vision
Physical exhaustion
Sleep disturbances
Headaches or dizziness
Anxiety patients often spiral into deeper anxiety when experiencing these symptoms:

"Why is my vision deteriorating so quickly? Am I going blind?"
"Why does my neck hurt so much? Is it thyroid disease?"
"My shoulders and back hurt—could it be a spinal issue?"
"My head hurts. Am I having a stroke or a brain tumor?"
However, taking a deep breath and allowing your body to relax can significantly alleviate or even resolve these symptoms. Most are just signs of over-exhaustion.

2. Emotional Fatigue
Emotional fatigue occurs when individuals feel emotionally drained, leading to reduced emotional responsiveness, diminished empathy, or difficulty regulating emotions.

Imagine being in a situation where traps are everywhere, and everyone is watching, waiting for you to make a mistake.

Under such stress, your body naturally reacts, becoming more sensitive and cautious to reduce errors. The brain generates fear, putting you on edge. Even the slightest disturbance can make you jump.

This prolonged tension can lead to nervous sensitization, where your nervous system becomes hyperreactive. Symptoms may include:

Muscle weakness, atrophy, or unnatural spasms
Sensations of numbness, tingling, or pain
Sweating excessively or, conversely, an inability to sweat
Dry, dull skin
Nervous sensitization acts as an amplifier, magnifying both your sadness and excitement. Even mundane sounds—car horns, heartbeats, or chewing noises—can feel overwhelmingly loud.

If you're fatigued emotionally, you might find yourself emotionally detached, unable to respond even when someone shares their joy or sorrow. It's not indifference—you're just drained.

3. Psychological Fatigue
Psychological fatigue refers to the mental exhaustion that comes from overthinking or prolonged cognitive strain.

Anxiety sufferers often struggle to relax their minds. Their thoughts race constantly, ruminating over:

Muscle fatigue symptoms
Past mistakes
Why they're so concerned about these mistakes
This excessive self-focus exacerbates mental exhaustion. Everyday life becomes a countdown; every second feels unbearably long, intensifying the anxiety.

They may fixate on perceived errors, replaying them repeatedly in their minds. Such rumination often leads to obsessive-compulsive tendencies.

For example, a woman deeply in love with her husband might suddenly think, "What if I stop loving him?" This intrusive thought becomes so persistent that she begins to believe it, even though it isn’t true.

4. Spiritual Fatigue
Spiritual fatigue involves reduced cognitive abilities like attention, memory, decision-making, and problem-solving.

Even small tasks feel insurmountable. Getting out of bed might feel like surviving the apocalypse.

Criticizing yourself—"You're lazy!"—and forcing productivity only worsens the situation, further depleting your mental reserves.

In Conclusion
Nervous fatigue encompasses four types:

Muscular fatigue
Emotional fatigue
Psychological fatigue
Spiritual fatigue
When left unresolved, these forms of fatigue can escalate into anxiety disorders.

So how can we address these types of fatigue and free ourselves from anxiety?

We’ll explore this in "How to Overcome Anxiety."