Am currently at home with a virus, one symptom of which is alternating hot sweats and shivering caused by a fever. I’ve had fevers before, but this time I’ve noticed a remarkably regular cycle to it.

At one extreme, I’ll be shivering uncontrollably while in bed wearing warm clothes and covered by all available blankets. Two hours later, I’ll be hot and sweating profusely while laying on top of the bed and wearing little. Two hours later I’ll be back to shivering. So far this cycle has been almost as regular as clockwork, which sparked my interest in the physiology behind it.

In a temperate part of the cycle I browsed the net and found this good explanation of fevers. I won’t attempt to summarise it, but it does explain the cycling back and forth between shivering and sweating. This cycle is normal - I just hadn’t noticed it being so regular and predictable before.