Does body temperature vary at different time of day?

Yes, body temperature can vary by about 1-2 degrees Fahrenheit throughout the day due to circadian rhythms. It tends to be lowest in the early morning and highest in the late afternoon or early evening before dropping again during sleep. This variation is related to our natural sleep-wake cycle and changes in hormone levels, especially cortisol and melatonin. Cortisol levels surge in the morning which raises the body's overall temperature preparation for activities, while Melatonin promotes lower temperatures closer to the late evening to aid in relaxation of preparation for sleeping.