A fever signals an elevated body temperature, which is 100.4°F (38°C) or higher. It is not an illness itself, but a symptom indicating immune system activation. It is a natural defense mechanism against infections, often caused by viruses or bacteria. The body’s “thermostat” in the hypothalamus raises the temperature set point, generating more heat.
The Body’s Response and Sleep’s Role
When a fever is present, the body combats infection, and sleep supports this process. Sleep redirects energy from daily activities towards immune functions, conserving resources needed to fight illness. During sleep, immune processes activate, including the production of cytokines that target infections and initiate the immune response.
Deep sleep (NREM stage 3) increases during infection, allowing the immune system to utilize more energy. This stage is important for body repair and recovery. The body’s fever response is more effective during sleep, as higher temperatures create a hostile environment for pathogens. Sleep also supports T-cells, specialized immune cells, in attaching more effectively to infected cells, enhancing their capacity to eliminate invaders. Prioritizing rest, especially sleep, strengthens the immune system’s ability to fight disease.
When to Seek Medical Attention
While rest is beneficial, certain fever characteristics and symptoms signal the need for medical evaluation.
For Adults
- Contact a healthcare provider for a temperature of 103°F (39.4°C) or higher.
- Immediate medical attention is necessary if a fever reaches 105°F (40.6°C) or higher.
- Seek emergency care if an adult’s fever is accompanied by severe headache, stiff neck, confusion, persistent vomiting, difficulty breathing, chest pain, rash, or seizures.
For Children
- For infants under three months, any rectal temperature of 100.4°F (38°C) or higher requires immediate medical attention due to their undeveloped immune systems.
- Children aged three to six months should see a provider if their rectal temperature exceeds 102°F (38.9°C), or if they appear unusually irritable or sluggish.
- For children aged seven to 24 months, a fever above 102°F (38.9°C) lasting longer than one day, especially with other symptoms like runny nose or cough, warrants a doctor’s call.
Regardless of Age
- Fever lasts longer than three to five days.
- Does not respond to fever-reducing medication.
- Accompanied by severe pain, difficulty swallowing, or dehydration.
Tips for Comfortable Rest
For individuals safely managing a fever at home, several strategies promote comfortable rest and recovery. Staying well-hydrated is important, as fevers lead to fluid loss and dehydration. Drinking water, clear broths, or oral rehydration solutions replenishes fluids and electrolytes. Avoid alcohol, tea, or coffee, as these contribute to dehydration.
Creating a comfortable sleep environment aids rest. Keep the room cool and use light, breathable bedding and sleepwear to regulate body temperature. While chilled, use a light blanket until chills subside, but avoid excessive layers that trap heat. Over-the-counter medications like acetaminophen or ibuprofen can help reduce fever and alleviate discomfort, though they do not cure the underlying illness. Always follow dosage instructions and avoid giving aspirin to children due to Reye’s syndrome risk.