AIMS: To determine how prevalent circadian rhythm impairments are in nurses working in medical, surgical and intensive care units in five Spanish hospitals and how the quality of night-time sleeping and sleepiness affect the nurses' morning and evening chronotypes.
BACKGROUND: Shift work is a recognized work pattern for nurses in all countries. Given the important role that nurses play in hospital care, it is vital to establish what repercussions this has on the nurses' working schedules and how any disturbance in circadian rhythm affects patient safety.
DESIGN: A multicentre, observational, descriptive and cross-sectional study in seven hospitals in the Spanish National Health System.
METHOD: A stratified sample of 1,300 nurses is being collected in three types of units: medical, surgical and intensive care. The 3-year study started in January 2012 and will continue until December 2014, with no exclusion criteria. The Kronowise(®) will be used to monitor the nurses' circadian rhythms, by recording their activity, position and wrist temperature. We will also use three questionnaires to evaluate sleep quality, daytime drowsiness and chronotype: (a) Pittsburg Sleep Quality Index; (b) Epworth Daytime Sleepiness Scale; and (c) Morning and Evening Questionnaire. Data will be collected from each hospital and statistical analysis will be carried out using the SPSS 19.0.
DISCUSSION: The study findings will show the current state of the nurses' circadian rhythms and how shift work can affect them and their job performance. Funding for this 3-year study was granted in December 2011 by the Spanish Health Research Fund (PI 11/00646, Health Ministry). This project is also funded by the Instituto de Salud Carlos III (RETICEF, RD12/0043/0011, RD12/0043/0006).
