A fever, an elevated body temperature, often accompanies illnesses. While generally a beneficial immune response, a fever can sometimes lead to disorienting experiences known as hallucinations, which are sensory perceptions that seem real but are not. This phenomenon, though unsettling, is usually temporary.
How Fever Affects Brain Function
An elevated body temperature significantly impacts brain function. Fever increases the brain’s metabolic rate, demanding more energy and oxygen. The brain is highly sensitive to even moderate temperature changes, which can disrupt the normal electrical activity of its neurons. Small increases in temperature, even less than 1°C, can lead to substantial changes in neuronal activity, sometimes causing neurons to become silent or overly excitable.
The body’s inflammatory response to an infection also plays a role in brain function during a fever. Inflammatory molecules, such as cytokines, are released into the bloodstream. These cytokines can cross the blood-brain barrier, a protective barrier. Once inside the brain, cytokines can influence brain cells and communication pathways, contributing to altered brain function.
Specific Causes of Hallucinations During Fever
The inflammatory response and circulating cytokines can directly interfere with neurotransmitter systems, chemical messengers crucial for perception and thought. Cytokines, for instance, can affect dopamine and serotonin systems, leading to confusion and altered perceptions. The brain’s attempt to regulate its temperature also impacts normal functioning, as the hypothalamus, the body’s thermostat, works to increase the set point, initiating the fever response.
Dehydration and electrolyte imbalances further disrupt neuronal signaling. Fever often leads to increased fluid loss and dehydration. Electrolytes like sodium and potassium are vital for carrying electrical signals between cells, and an imbalance can disrupt this process, leading to confusion.
Sleep deprivation and the development of delirium can also contribute to fever-induced hallucinations. Prolonged sleeplessness can lead to perceptual distortions and complex hallucinations. Delirium, acute confusion, is more likely to occur with severe or prolonged fevers and can manifest as confusion and hallucinations.
When to Seek Medical Attention
While fever-induced hallucinations are often temporary and resolve as the fever subsides, certain signs warrant medical consultation. Seek medical attention if an adult’s fever is 103°F (39.4°C) or higher, or if a child’s fever is over 102°F (38.9°C) for children over three months, or 100.4°F (38°C) for infants under three months.
Other concerning symptoms include persistent or worsening hallucinations, confusion or disorientation, a stiff neck, severe headache, or unusual sensitivity to light. Any rash, difficulty breathing, chest pain, or seizures accompanying a fever also necessitate immediate medical evaluation. Consulting a healthcare professional is particularly for infants, young children, or individuals with pre-existing health conditions.