Aim: 

Recently our group proposed peripheral skin temperature circadian rhythm, measured on the wrist (WT), as a marker rhythm for circadian system assessment in normal living humans. The aim of the present study was to establish the relationship between chronotypes (as evaluated by the Horne & Otsberg questionnaire, HOQ) and circadian WT pattern characteristics in young Spanish population.

Methods: 

WT was recorded by a data logger (Ibutton, Dallas) in 120 young adults from 22 to 24 years old, every 10 min during a complete week. Temperature sensor was positioned in the wrist of non dominant hand. The subjects filled in a sleep diary and completed the HOQ. All data were submitted to temporal series analysis, and mesor, amplitude, acrophase, Fourier harmonics and Rayleigh vector obtained.

Results: 

When comparing chronotype classification of our young population (evening, morning and neither type) using the HOQ with the acrophase of the WT pattern, a significant high correlation appeared. The relationship between WT circadian pattern and sleep by chronotype was described using the beginning and the end of sleep as a "zeitgeber time". Thus, the WT rhythm in the morning type showed a statistically significant phase advance at the beginning of sleep when compared to the evening type, while neither type showed an intermediate pattern.

Conclusions: 

WT recordings have proved to be, not only a useful technique to assess circadian system functioning, but also able to characterize chronotypes with high sensitivity and precision without the subjective interference associated to the HOQ.

This project was funded by Seneca Foundation (PI/05700/07), by Instituto de Salud Carlos III (RETICEF, RD06/0013/0019), and by the Ministry of Education and Science (BFU2007-60658/BFI).