Internal tremors are described as a sensation of shaking or vibration felt deep inside the body. This phenomenon is often confusing because the person feels a definite, sometimes intense, movement that is not visible externally. The subjective nature of the feeling often leads to anxiety, as the internal tumult contrasts sharply with the body’s apparent stillness. This internal shudder is frequently a physical manifestation of an overactive nervous system and warrants investigation to determine its underlying cause.
Describing the Internal Shudder: The Subjective Sensation
The experience of an internal tremor is often described using sensory metaphors, as if a small, rhythmic energy is trapped beneath the skin. Many people report the sensation feels like a cell phone vibrating on silent mode, often localized in the torso, limbs, or head. This internal buzzing or quivering is a deep sensory experience, sometimes described as an electrical current running just below the muscle layer. The feeling can be sporadic or constant, often becoming more pronounced during periods of rest or when trying to fall asleep.
The intensity can range from a subtle, low-frequency hum to a disruptive, jittery feeling that makes sitting still difficult. Unlike the observable shaking of an external tremor, the movement is generally too subtle to be detected by the naked eye. This lack of visible evidence can make the symptom difficult to explain to others or to healthcare providers. The subjective sensation indicates neurological activity that is not translating into a large-amplitude physical movement.
Internal vs. External Tremors: Key Differences
The primary distinction between internal and external tremors lies in their visibility and clinical classification. External tremors involve observable, rhythmic, involuntary movements of a body part, such as a hand, voice, or leg. These visible movements are categorized based on when they occur, such as a resting tremor when the limb is relaxed, or an action tremor during voluntary movement. External tremors have a measurable frequency and amplitude that can be quantified by a physician.
Internal tremors, conversely, are defined by the lack of visible movement, existing primarily as a subjective sensory experience. They are considered a sensory symptom rather than a motor symptom, despite the feeling of shaking. Researchers suggest that internal tremors may stem from the same neurological causes as external tremors, but the movement is too small in amplitude to be easily seen. This means the underlying mechanism of rhythmic muscle contraction may be present, but the physical manifestation is contained within the body.
Common Causes of Internal Tremor Sensations
The sensation of internal trembling can be linked to a variety of physiological and psychological conditions, all of which affect the nervous system’s regulation of muscle activity. One frequent cause is heightened anxiety and stress, which triggers the sympathetic nervous system’s fight-or-flight response. This response floods the body with stress hormones like adrenaline, increasing heart rate and muscle tension. This results in a persistent, low-level activation of the muscles, leading to the subjective feeling of internal jitteriness.
Medication side effects or withdrawal are another common source of internal tremors. Certain drugs, including some antidepressants, asthma medications, and stimulants, can over-excite the central nervous system, causing generalized internal vibrations. Similarly, the sudden cessation of substances like alcohol or caffeine can trigger withdrawal symptoms that present as internal shaking. The nervous system attempts to re-regulate after the external influence is removed, creating a period of instability.
Neurological and Metabolic Factors
Internal tremors are also reported by people with neurological movement disorders, such as Essential Tremor and Parkinson’s disease. Essential Tremor is one of the most common movement disorders, and the internal feeling may precede the development of visible shaking or exist alongside it. For people with Parkinson’s disease, internal vibrations are a common non-motor symptom related to the underlying loss of dopamine-producing cells.
Metabolic imbalances can also contribute to the sensation, notably low blood sugar (hypoglycemia) and thyroid dysfunction. Hypoglycemia causes the release of adrenaline that results in shakiness. An overactive thyroid gland (hyperthyroidism) generally increases the body’s overall metabolic rate, which can manifest as tremors. General fatigue and muscle overexertion can also lead to muscle exhaustion and instability, which may be perceived as an internal quiver.
When to Seek Medical Guidance
While internal tremors are often benign or linked to manageable factors like stress, they warrant a medical evaluation if they are persistent or accompanied by other symptoms. A doctor’s visit is recommended to determine the underlying cause and rule out more serious neurological or systemic conditions. It is particularly important to seek guidance if the internal shaking occurs alongside unexplained muscle weakness, trouble walking, dizziness, or numbness. These accompanying signs may point toward a condition affecting the central nervous system.
When preparing for a medical consultation, keep a detailed symptom diary. Document the timing of the tremors, their duration, location, and any potential triggers, such as stress or medication use. A physician will typically perform a comprehensive physical and neurological exam to test reflexes, balance, and coordination. They may also order blood tests to check for metabolic issues, such as thyroid problems or vitamin deficiencies, to help narrow down the possible causes.