Related Experiment Video
Updated: Jun 9, 2026

Through-the-Wall Blood Sampling Method to Minimize Sleep Disruption in Clinical Settings
Published on: June 13, 2025
Influences of sleep and the circadian rhythm on iron-status indices
Peter Ridefelt1, Anders Larsson, Javaid-ur Rehman
1Section of Clinical Chemistry, Department of Medical Sciences, Uppsala University, Uppsala, Sweden. peter.ridefelt@medsci.uu.se
Objectives:
The aim was to study the influence of sampling time, food intake and sleep on tests used to screen for and monitor conditions of iron deficiency and overload.
Design And Methods:
The 24 h variations of iron, transferrin, transferrin saturation (TS) and ferritin were studied in seven healthy individuals during standardised food intake, and during night or day sleep.
Results:
Iron and TS showed clear diurnal variations, with peaks at 12.6 h and 12.8 h respectively, during night sleep, and at 19.7 h and 19.3 h, respectively, during day sleep. Ferritin did not demonstrate any circadian variation. Transferrin and ferritin were unaffected by sleep-condition. Meals did not have any effect except a slight decline of transferrin.
Conclusions:
Time of day and sleeping patterns had great influence on iron and TS, whereas no or only minor effects are seen on the concentration of ferritin and transferrin. Meals have limited effects.
Related Concept Videos
Insufficient Sleep and Sleep Deprivation
Sleep deprivation is a more severe form of sleep loss...
Circadian Rhythms and Gene Regulation
Circadian Rhythms and Gene Regulation
Understanding Sleep
The circadian rhythm, a nearly 24-hour cycle, is deeply influenced by environmental light cues. Light exposure directly affects the hypothalamus, which in turn regulates...
Chronopharmacokinetics: Circadian Rhythms and Influence on Drug Response
The time of drug administration is an important factor to consider, as it can influence the toxic dose of a drug. For example, a study conducted by Prins et al. in 1997 examined the effects of the timing of...
Substance Use Disorders Affecting Sleep
Understanding the concepts of physical dependence,...

