Regulan fever is a medical condition known to afflict humanoids in the 23rd century.
History and specifics[]
Sufferers of Regulan fever require frequent naps, sometimes hourly.
In 2274, Christine Chapel considered the possibility that Zeta-Atez's Imperator Dykranus might have Regulan fever. Leonard McCoy thought the symptoms could also apply to encephalitis lethargica. (TOS comic: "Heads of State")