Does the Time of Day Affect Your Body Temperature?
According to the National Institute of General Medical Sciences, the time of day affects the body temperature through a physiological phenomenon called circadian rhythm. The UCLA Sleep Disorders Center explains this cycle is controlled by small nuclei in the brain, called the suprachiasmatic nuclei, along with other circadian rhythms.
The UCLA Sleep Disorders Center also states that the body temperature is the lowest during the night, reaching a minimum at around 4 a.m., according to Wikipedia. The UCLA Sleep Disorders Center further notes that the temperature starts to rise before waking up, but drops slightly again between 2 p.m. and 4 p.m. Wikipedia claims that the body temperature reaches its peak during the late afternoon, between 4 p.m. and 6 p.m.