Restless Legs Syndrome (RLS): Characterized by an irresistible urge to move the legs, but it can also affect the hands. It's often associated with uncomfortable sensations and can be exacerbated by rest, especially in the evening.

Anxiety or Stress: Can cause fidgeting or restlessness in the hands due to increased nervous energy.
Akathisia: A movement disorder characterized by a feeling of inner restlessness and a compelling need to be in constant motion, often seen as a side effect of antipsychotic medication.
Parkinson's Disease: Early stages can present with restlessness or fidgeting in the hands due to motor symptoms.

Thyroid Storm: Although rare, hyperthyroidism can cause significant restlessness and agitation, including in the hands, and is a medical emergency if not promptly treated.
Neuroleptic Malignant Syndrome (NMS): A life-threatening neurological disorder most often caused by an adverse reaction to neuroleptic or antipsychotic medication, which can present with agitation and restlessness.
Serotonin Syndrome: A potentially life-threatening medical condition resulting from an excess of serotonin in the central nervous system, which can cause restlessness among other symptoms.

Wilson's Disease: A rare genetic disorder that leads to copper accumulation in the body, affecting the brain and liver. It can cause movement disorders, including tremors or restlessness.
Huntington's Disease: An inherited disorder that causes progressive damage to the brain, leading to physical, cognitive, and psychiatric problems, including chorea (involuntary, abrupt movements) that could be perceived as restlessness.
Dystonia: A movement disorder that causes involuntary muscle contractions, leading to repetitive movements or abnormal postures, which could manifest as restlessness in the hands.