So, often with a cold or other symptomatic respiratory illnesses you wake up feeling congested, headachy and crappy because your cold meds you take to treat your symptoms like NyQuil or Advil + pseudoephedrine or whatever you like to take wears off while you sleep. As soon as you hydrate and your first dose of your morning meds kicks back in, you start to feel better and you stay that way during most of the day while medicating, hydrating, and doing other things that make you feel better.
Fever, however, is another matter. Fever is low during the early morning and picks up and rises in the late afternoon. Why? Because It follows your natural circadian rhythm of body temperature. Human body temperature is not static at 98.6 degrees F. Body temperature regularly fluctuates about a degree (peak to trough) or a degree and a half throughout the 24 hour day-night cycle.
Humans are primarily diurnal creatures which just means we are active during the day and sleep at night. Body Temperature begins to climb just before you wake up and continues to rise during the day peaking around 4:00-ish for most folks. Then it slowly begins to fall before you return to sleep and it stays down until the next morning when it starts to rise again.
Fever follows this natural circadian trend and usually is low or almost non existent first thing in the morning and is at its worst in the late afternoon/early evening. (So don’t assume you don’t have fever by just looking at your morning temp. Check it again 2-4 pm). An illness with fever will usually make you feel worse when your fever is highest in the late afternoon not when it’s at its lowest in the morning.
Viral Infections get worse during the night, bacterial infections worsen during the day. Fighting a bacterial infection takes rest, but a viral attack seems to worsen with complete rest.
“Feed a cold, starve a fever.” Stay awake for the cold, sleep for the fever. Learned part of this from the Professor on Gilligans Island.
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