Fever at Night (Gone in the Morning): Causes &Treatment

A fever at night gone in the morning is often the result of the hypothalamus becoming more active during natural sleep cycles. This part of the brain regulates body temperature and may trigger heat spikes while the body fights simple infections like a cold.

While frequently caused by mild viruses or environmental factors, these temperature fluctuations can occasionally signal chronic conditions like lupus or tuberculosis. The increased body heat often leads to excessive sweating or sudden chills that may disrupt sleep patterns.

Medical assessment is necessary if the fever persists for more than three days or does not improve with standard pain relief medication. Treatment depends on the underlying cause and may involve prescribed antibiotics, anti-inflammatories, or antivirals to eliminate the infection.

Why fevers worsen at night

In most cases, fevers emerge or worsen at night due to the cyclic functioning of the hypothalamus. The hypothalamus is a part of the brain that is responsible for producing hormones that regulate body temperature. It becomes more active at night, which can lead to an increase in body temperature when you are sleeping. 

In addition, due to normal metabolic functioning, it is normal to expect an increase in body temperature as the day progresses. Temperature hits a peak at night time, which can lead to increased sweating. 

Fevers at night are rarely a sign of a serious health problem, and are usually related to an infection. Nonetheless, if you experience night fevers for more than 3 days, you should see a doctor for assessment, as you may need targeted treatment to treat the underlying cause. 

Common causes 

A fever is one of the body’s natural defense mechanisms and can occur for many reasons, such as: 

• Viral infection, like a cold, flu or COVID-19 
• Bacterial infection
• During an auto-immune disease flare-up, like rheumatoid arthritis or Crohn’s disease
• As a side-effect of certain medications that decrease immune system functioning 
• Following a vaccine 

It is important to identify the underlying cause of the fever, so that appropriate treatment can be started as necessary. Read more about other common causes of night sweats and what to do. 

What to do

To treat fevers that are caused by infectious, it is important to first determine the infectious agent, as this will ultimately guide treatment. The doctor can prescribe antibiotics, anti-inflammatories, anti-pyretics and/or antivirals to eliminate the infection, which will then treat the fever.  

When treating a fever, you should also opt for well-ventilated rooms and light clothing, and be sure to rest and bathe in warm water.  Read more about how to break a fever at home and when you should see a doctor. 

When are night fevers serious?

Night fevers are rarely a sign of a serious health condition, even if the underlying cause is not totally known. These types of fevers are most commonly triggered by environmental factors, like increased room temperature or using too much clothing, both which can accelerate systemic metabolism.

There are some illnesses, however, in which daily night fevers are one of the only symptoms. Some examples include: 

• Lyme disease
• HIV
• Tuberculosis
• Hepatitis
• Lupus

Some types of cancer can also initially present with night fevers, however other symptoms eventually emerge, like weight loss for no apparent reason.