There is an optimum temperature at which all our metabolic activities happen without any problem. This normal body temperature is 36.5-37.5 degree Celsius. This temperature is maintained throughout the day by that part of the brain which is called hypothalamus. There are many factors that help it do so. The light regulations of day and night are one such factor that helps in regulating the body temperature. When the body temperature rises above this optimum range the condition is called fever. Most of the fevers are not harmful. They can be the indication that the body is fighting against a foreign microbe that can affect your body badly. And so if you have an active immune system, it is obvious that you will get fever at times. It is just a part of your body’s defence mechanism. Fever is accompanied by a rise in temperature. This is a fact that everyone knows, isn’t it? Another point or a question that bothers most of the parents is that the fever gets serious at night time. But the very next morning everything may be quite alright. This rise of temperature and increase in the intensity of fever at night is a common phenomenon. The main reason behind this is that naturally the body temperature rises at night. So at the time of fever it may go beyond what is considered normal.
Night is a time when the body heals itself. It is the time when all the metabolic activities are at its heights. Normally at night the body temperature undergoes a slight increase. You can observe this by yourself with the help of a thermometer. There is a biological clock inside our system. It naturally gives the timing to our body. It is actually a hormone called melatonin. The SCN, superchiasmatic nucleus is a part of brain that helps or regulates the secretion of melatonin. It contains a sort of pacemaker which tunes the body to act according to the time set in the biological clock. Thus it helps in creating a natural rhythm in our body. When it is morning and the sunlight enters to the eyes, the secretion of melatonin is reduced under the regulation of SCN. And as the time passes we get more active and start to dissipate more energy which causes the body temperature to rise. This happens at night also. The only thing is that the process starts off from already higher temperature. So the body temperature rises at night. Another reason is that at night as the blood pressure decreases, the defence mechanism drops down. This makes the microbes especially viral attacks more powerful and hence the fever spikes.
The studies on the effect of time on body functioning is still progressing. This branch is called chronobiology. There is not much information in this matter. So there is not much to worry when the fever rises at night and becomes normal at day. This is just natural and do not cause much harm up to when the temperature does not crosses a certain limit.