Changes in the circadian rhythm of serum iron induced by a 5-day sleep deprivation.

The effect of 5 days of sleep deprivation on the circadian rhythm of serum iron was studied in a group of six healthy male volunteers. The results were compared with a control group of five individuals, whose normal sleep cycle was preserved, but whose daily regimen was otherwise identical with the sleep deprivation group. Their biorhythm was processed mathematically using cosinor analysis. Sleep deprivation markedly reduced the mean level of iron, diminished the absolute and relative amplitude of oscillations, disturbed the shape of the daily course of serum iron and gradually decreased the computative acrophase, i.e., shortened the period of rhythm. Forty-eight hours of recovery resulted only in a partial normalization of all the observed changes. The potential mechanisms of the observed changes are discussed.