We have all have experienced fevers, there are many different beliefs about it in different cultures and multiple ways to treat it, ranging from modern medicine to ancient practices. When one has a fever, their body feels warm and weak, they also do not have energy to do extended movements. As fevers are a range, some being slight to others being signs of dangerous conditions, dealing with them can be tricky. Things like fever dreams, conversations and thoughts are often incoherent. There are things called fever hallucinations as well, but why does this happen? Fever means your body temperature has gone above what's normal. But what's "normal" can be a bit different for everyone and can change based on how active you are and the time of day. Generally, a fever is when your temperature is higher than 99 degrees Fahrenheit in the early morning or above 100 degrees Fahrenheit at any other time.Do Fevers Make Us More Irritable? In a 2013 review published in the Journal of Pain and Symptom Management, the researchers found that not only do fevers cause people to feel cold, weak and other bodily sensations, but the participants also expressed emotional changes, vivid dreams/hallucinations. In one of the interview with a participant from the study, researches noted them experiencing feelings of anxiousness, crabby, angry and frustrated, “Like I said, I think fever is really tied in to how you feel emotionally. Because I know every time I have a fever, I just get snotty, for lack of a better term, because I'm just really agitated.” “I feel tired. I feel irritable” How Is Body Heat And Brain Health Connected?Harvard Heath explains a part of your brain called the hypothalamus acts like a thermostat for your body. When you're healthy, it keeps your body at its usual temperature. A fever happens when the hypothalamus gets set to a higher temperature than normal. This change in the brain's thermostat is usually caused by tiny things in your blood called pyrogens. According to a 2023 review by Yale School of Medicine heat can change things in the environment, it can also change how our brains work. In a study, researchers found that even small increases in temperature while the brain is active can really change what the brain does, and sometimes these changes can be negative. Experts from Yale explain that changes in temperature in the brain also affect how our nerve cells (neurons) fire signals. These cells have tiny pumps that give them electrical energy, which they release when the brain is active. The researchers found that if brain cells get heated up too fast, faster than these pumps can adjust, the cells might become more active or less active than usual. Even tiny temperature changes from brain stimulation can lead to big changes in neuron activity. As neurons get warmer, they can even stop working, and when they cool down again, they can become very easily excited. Fever Hallucinations and other Psychological AffectsAccording to an Infections & Chemotherapy 2022 review, fevers can cause febrile convulsions, which is a seizure caused by a fever in young kids. It can also cause confusion, like not understanding where you are, not recognizing your surroundings. It can also cause unstable emotions, conscious and cognitive disturbances like illusions on hallucinations. These can also be symptoms for things like influenza infections or encephalitis. Like the Yale experts explained even small temperature changes can have such a big impact on brain activity, we need to start paying attention to these small changes. He points out that it's a basic rule of physics that when you send electricity through wires to stimulate the brain, you will create heat, both in the wires and in the brain tissue itself. Researching more on these matters can help us find better treatments and help doctors change the course of several procedures to help their patients.