Internal vibration sensations: the hum nobody else can see.

A shaking or buzzing felt inside the chest, belly or legs, with nothing visible on the outside, is common, harmless, and very often a sensitized nervous system.

This page is about understanding the condition and the role the brain and nervous system can play in it. It is not a diagnosis. Your own clinicians know your case.

What internal vibration sensations are

People describe it in many ways: a phone vibrating in the chest, an engine idling in the belly, a hum in the legs at night, a shiver running through the body that never quite surfaces. The defining feature of an internal tremor is that it is felt but not seen. Hold out your hands and they are steady; lie still and the buzzing continues.

Internal tremors are well recognised in Parkinson's disease, where they can precede visible tremor, and in multiple sclerosis and essential tremor. They are also common in anxiety and panic, where adrenaline and muscle tension create a fine, invisible shaking. More recently, they have been reported by a large share of people with long COVID.

In every one of these settings, internal tremors are not dangerous. They do not damage anything. They are a sensation, and the question is what is generating it.

The neuroplastic contribution

The ATNS Index of Neuroplastic Symptoms advises that if there is no Parkinson's disease, multiple sclerosis or essential tremor, assessment for neuroplastic symptoms is likely to be helpful.

Neuroplastic symptoms are real symptoms produced by learned pathways in the brain and nervous system, a sensitized alarm system, rather than by ongoing damage or disease in the body. They are not imaginary and not 'all in your head'. Because the brain can change, they are reversible.

Internal vibration is a classic product of a nervous system on alert:

• The stress response raises adrenaline and muscle tone throughout the body. Fine muscle activity below the level of visible movement is felt as buzzing or shaking.
• The brain constructs sensation from signals and predictions. Once it has learned to expect a vibration, it generates one readily, especially at rest when there is little else to attend to. This is the sensory face of central sensitization.
• Attention locks on. Lying in bed scanning for the hum makes the hum louder, and the fear that it signals a serious disease keeps the alarm running.
• Internal tremors often travel with other neuroplastic symptoms: tingling, dizziness, palpitations, fatigue, brain fog.

The related index entries for tingling sensations, essential tremor and long COVID fill in the surrounding picture.

What the research shows

Research on internal tremors specifically is limited, and no study has directly tested a neuroplastic explanation, so the evidence is indirect but consistent.

A cross-sectional study of 423 adults with long COVID found that 158, about 37 percent, reported internal tremors or a buzzing or vibrating sensation. Those with internal tremors had worse quality of life, more financial difficulty and higher rates of other new neurological and mast-cell conditions. The study documents how common and how distressing the symptom is, and the authors note that until recently internal tremors had mostly been described in Parkinson's disease and essential tremor, where they were linked to anxiety and other sensory complaints.

A case-control study of 102 patients with functional sensory symptoms, the group whose nerves and brain scans are normal, lists internal vibrations among the sensations they report, alongside tightness, pressure, electricity-like feelings and altered temperature sensation. Internal vibration, in other words, is a recognised symptom of a nervous system producing sensations without structural cause.

A review of the management of functional neurological disorder describes abnormal sensation as part of the spectrum of FND and summarises the treatment approach: clear explanation of the diagnosis, retraining of attention and movement, and psychological therapies, all of which rest on the brain's capacity to relearn.

The honest summary: once the few neurological diseases that cause internal tremor have been excluded, the sensation is best understood as a sensitized nervous system doing what sensitized systems do.

Signs the brain may be part of the picture

• A neurologist has found no sign of Parkinson's disease, multiple sclerosis or essential tremor.
• The vibration is strongest at rest, in bed or when you focus on it, and fades when you are busy or absorbed.
• It moves: chest one day, legs the next, sometimes the whole body.
• It began during or after a stressful period, an illness such as COVID, or a health scare.
• It comes with other sensations: tingling, dizziness, racing heart, muscle twitches, fatigue.
• Worry about what it means is a large part of the experience.

A solution that addresses it

Once neurological disease is excluded, the sensitized nervous system is the target, and an approach exists that addresses it: pain and symptom reprocessing, which applies to sensations as much as pain. It combines education about neuroplastic symptoms, somatic tracking (observing the vibration with curiosity rather than dread), reducing threat, graded return to activity and rest without scanning, emotional awareness and expression, and acceptance and commitment skills. Trained clinicians deliver these approaches, and digital programs increasingly make them available at home. ACT helps you let a harmless sensation be present without fighting it, and somatic practices teach the brain that the hum is safe.

Cindra is a daily AI companion built around these approaches, with daily check-ins, short practices and plain-language lessons for people whose symptoms have a neuroplastic component. If the buzzing inside has outlasted every reassurance, you can join the waitlist.

What to do next

See a clinician and, if needed, a neurologist, to check for Parkinson's disease, multiple sclerosis, essential tremor, thyroid problems and medication effects. Internal tremor with visible tremor, stiffness, slowness, weakness, vision changes, balance problems or numbness needs prompt neurological assessment. Do not stop any medication without advice.

If the evaluation is reassuring, ask whether the sensation fits a neuroplastic pattern. If it might, start learning and practising. The FND guide and, if your symptoms began after COVID, the long COVID guide are the natural next reads.

This article is for general education and is not medical advice, and it does not diagnose or treat any condition. Persistent symptoms deserve a proper medical assessment to rule out disease or injury before a neuroplastic explanation is considered. If your symptoms are new, changing, or come with red-flag signs such as fever, unexplained weight loss, numbness or weakness, chest pain, or loss of bladder or bowel control, see a clinician promptly.