• Nerves and nervous tissue – exhaustion, neurasthenia, mental weakness
• Mind – anxiety, depression, mental overwork
• Muscles and spinal cord – weakness, trembling, fatigue
• Cerebrospinal axis – nervous debility, sensory-motor disorders
• Heart – palpitations from nervous causes
• Sleep centres – insomnia from overstrain

• Rest
• Gentle warmth
• Nourishing food
• Mental relaxation
• Quiet environment
• Short naps or sleep

• Mental exertion
• Emotional stress
• Noise and light
• Talking or social interaction
• Excessive stimulation
• After coition
• Grief, disappointment

Kali phosphoricum is one of the deepest-acting nerve tonics in the materia medica. It is indicated in states of mental prostration following grief, overwork, or illness. The patient is often apathetic, indifferent, or hopeless, overwhelmed by their responsibilities, and lacking motivation or will. Memory is impaired—words are forgotten mid-sentence; names, facts, and thoughts vanish. [Kent] remarks upon the “mental weariness” after years of toil, particularly in students, scholars, and sensitive types.

There is irritability, anxiety, and hypersensitivity to impressions. The slightest noise unnerves them. The patient becomes isolated, withdrawn, and suffers from fear of people, fear of insanity, and inability to cope with daily life. Suicidal thoughts may arise, especially at night, though they are passive and unaccompanied by active intent. Depression alternates with nervous excitement, particularly in artistic or intellectual individuals.

Headaches arise from mental exertion, worry, or emotional strain. They are often pressing or heavy in nature, located in the forehead or vertex. The scalp feels sore and oversensitive, with a sensation as if the brain were shaking or too loose. Vertigo may come on from reading or thinking. [Clarke] mentions headaches that begin in the morning and worsen through the day. The pains are often accompanied by mental dullness or eye fatigue.