Effects of Shift Work on Nurse Staff Health
Condition: Shift Work Type Circadian Rhythm Sleep Disorder; Chronobiology Disorders; Mood Swing; Physical Activity; Cardiovascular Diseases
MeSH terms: Sleep Wake Disorders; Sleep Disorders, Circadian Rhythm; Chronobiology Disorders; Cardiovascular Diseases
Study type: Interventional

Summary: 
      Shift work deeply impacts on temporal organization leading to a circadian desynchronization,
      which translates into a worsening of the sleep quality and work ability during waking hours.
      Furthermore, also the fine motor control skills and the subjective mood profile could undergo
      modifications in relation to the acquired sleep debt. The misalignment between working time
      and physiological/behavioral functions could have negative influences on the levels of
      spontaneous daily activity, with possible alteration of the activity-rest rhythm of the
      worker, especially in clinics.

      In relation to the participants' chronotype, the aim of this project will be to evaluate the
      effect of irregular working hours (shift work) on (i) the sleep quality, (ii) the circadian
      rhythm of activity levels and, (iii) the motor control. These assessments will help to
      identify the shift type with less impact on the health status in a nurse cohort.
    

Detailed description: 
      Shift work can exert numerous effects on the temporal and behavioral organization of the
      individuals. Working hours of shift workers, which are outside the normal daily social
      program, lead to a circadian desynchronization due to a temporary misalignment between
      working time and physiological and behavioral functions, similarly to what is observed in the
      jet lag syndrome. This may lead to deterioration in the sleep quality, reduction in the
      working ability during waking hours, with sleepiness and a reduction in the vigilance state.

      Over the years, the impact of shift work has involved many areas and its effects have been
      investigated at the cardiovascular (coronary artery disease, hypertension), metabolic
      (diabetes and obesity) and immunological level. Several investigations provided evidence of
      the shift work-induced negative results on health, including carcinogenic effects.
      Consequently, the scientific community paid to these problems great attention.

      In analyzing the health effects of shift work, the chronotype of the workers, or their
      circadian typology, is very important. In fact, the circadian rhythms represent a dimension
      of the human personality that should not be underestimated. The human being has a temporal
      organization, determined by the interaction of endogenous and environmental factors, and
      organizes most of the biological and behavioral activities according to a twenty-four hour
      period and in sync with the light-dark cycle. It is not worthy to mention that the biological
      rhythms in humans present interindividual differences that determine precisely the
      chronotype, which is the tendency to express preferences toward morning or evening
      activities. Within the population, it is possible to recognize subjects that can be traced to
      three circadian types: (i) morning-types subjects (M-Types) that tend to be more active and
      efficient in the first part of the day, (ii) evening-types subjects (E-Types) who find it
      difficult to get up in the morning and require more time to reach the optimal level of
      physical and mental efficiency, and (iii) intermediate subjects (Neither-Types, N-Types) that
      present intermediate characteristics between the previous two.

      Previous studies suggested that the eveningness could determine an easier adaptability to the
      changes determined by shift work. However, the role of the chronotype on this aspect is yet
      to be related to the type of shift: on one side, the E-Types tend to have more sleep
      disorders induced by a diurnal working shift. On the other side, the M-Types tend to adapt
      worst to a night working shift. In any case, shift work determines a growing sleep debt that
      can have a not negligible impact on the wellbeing and health of the individual.

      The association between shift work and cardiovascular risk is very interesting. Sleep at
      night, in fact, can have important effects on blood pressure. Some studies have shown that a
      good sleep quality may have potential effects in the prevention of hypertension. Arterial
      pressure decreases by an average of 10-20% during nighttime hours, so sleep debt could lead
      to higher average blood pressure over the course of twenty-four hours. In addition, by
      modifying the circadian rhythms, the shift may lead to an alteration of the autonomic nervous
      system regulation with hypertensive consequences.

      This project will focus on a particular category of shift workers, i.e., the nurse staff
      working in a hospital. Nurse staff has three different shift schedules: (i) shift changes
      every day (the first day from 7.00 to 14.00, the second day from 14.00 to 21.00, the third
      day from 21.00 to 7.00, the fourth day night off and, the fifth day rest), with a "shift
      cycle" duration of 5 days; (ii) shift changes every two days (first and second day from 7.00
      to 14.00, third and fourth day from 14.00 to 21.00, fifth day rest, sixth and seventh day
      from 21.00 to 7.00, eighth day night off and ninth and tenth day rest), with a shift cycle of
      10 days; and (iii) only diurnal shifts (first day from 7.00 to 14.00 and the second day from
      14.00 to 21.00), with 2 days of rest every 5 work days.

      To this purpose, the aim of this project will be to identify the type of shift work schedule
      with less impact on the state of health of the hospital staff by evaluating the effect of
      different shift work schedules on the quality of sleep, on the circadian rhythm of activity
      levels and on motor control, in relation to the participants' chronotype.
    

Intervention name(s): Shifts working hours with different schedules
Intervention type(s): Other
Intervention description(s): Workers in Group 1, 2, and 3 will undergo three different shift work modalities presenting different schedules.
Importantly, as an inclusion criteria, workers have to be involved in the same shift modality for at least one year at the time at the beginning of the study.
Allocation: Non-Randomized
Intervention model: Parallel Assignment
Intervention model description: Participants are divided in three different groups on the bases of their actual shift work modalities. Thus no allocation process is possible within this project.
Masking: None (Open Label)
Primary purpose: Other
Keywords: Chronotype; Shift work; Health status