Biological Rhythms Impact of 12 Hours Shift Work

Study Overview
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Brief Summary
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Nonstandard time-schedules work are widespread in the world of work. Shift and night work have been shown to be responsible for a desynchronization of biological rhythms, associated with melatonin secretion impairment and sleep disturbances. However, while health consequences of night and shift work are widely recognized and represent a major public health concern (High Authority of Health 2012 Recommendations and National Agency for Public Health Food, Environment and Work 2016 Report), the mechanisms by which the circadian system is affected by shift work remain poorly understood. Indeed most of the studies in the fields are cross-sectional, based on few blood or urinary samples in a single work position, in workers whose shift work patterns are often misidentified and heterogeneous. Moreover, few studies have assessed melatonin secretion alterations in relation to objective sleep measurement (actigraphy). The aim of this study is to assess the dynamics of melatonin secretion adaptation in 12-hour shift work and to correlate these data to sleep-wake cycle recording.

Official Title
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Wake-sleep Cycle and Melatonin Secretion Dynamics Associated With 12 Hours Shift Work in French Nurses

Conditions
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Shift-Work Sleep Disorder

Intervention / Treatment
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* Other: melatonin and cortisol sampling


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Nurses or nursing assistants working in the Sleep and Respiratory Diseases Department of the Croix-Rousse Hospital with positions in 12 hours for more than 6 months informed consent given by the subject Exclusion Criteria: Pregnancy or lactation <6 months Taking treatment modifying the secretion of melatonin (melatoninergic drugs (including antidepressants), beta-blockers) Refusal of participate Minor or major protected subject Not affiliated to a social security scheme Participant in another interventional study interfering with sleep / wake rhythm or work schedules (judgment of the investigator)

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 65 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Diagnostic
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: melatonin and cortisol sampling<br>14 healthy volunteer nurses working on 12 hours night/day schedules in the Sleep Medicine Center of Lyon. | Other: melatonin and cortisol sampling<br>* The study will take place over 15 days during which the nurses will wear an actigraphic wristband and will fulfill a sleep log. During 3 periods of 24 hours selected during these 15 days, including a 12h day shift (Day 2), a 12h night shift (Day 8) and a rest (Day 13), the participants will collect their urine by 4 to 8 hour periods, note the corresponding urine volumes and for each period, sample a 5 mL tube which will be analyzed later (6-sulfatoxymelatonin and urinary cortisol assays). The subjects will complete questionnaires at the beginning of the study (Horne and Ostberg, Insomnia Severity Index, Epworth, Pichot, Hospital Anxiety and Depression) and the days corresponding to the urine sampling (Karolinska and St Mary Hospital).<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| total amount of melatonin excreted during the sleep period for the night shift | The impact of 12H shift work on melatonin secretion dynamics will be assessed by comparing the total amount of melatonin excreted during the sleep period between the 12h day shift condition and the 12h night shift condition | at day 8 (night shift) | 
| total amount of melatonin excreted during the sleep period for the day shift. | The impact of 12H shift work on melatonin secretion dynamics will be assessed by comparing the total amount of melatonin excreted during the sleep period between the 12h day shift condition and the 12h night shift condition | at day 2 (day shift) | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Total amount of melatonin excreted during the sleep period at rest | the total amount of melatonin excreted during the sleep period at rest will be compared to the total amount of melatonin excreted during the sleep period for the 12h day shift condition ant to the total amount of melatonin excreted during the sleep period for the 12h night shift condition | at day 13 (rest) | 
| Melatonin secretion dynamics in 12h day shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 2 (day shift) | 
| Melatonin secretion dynamics in 12h day shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 2 (day shift) | 
| Melatonin secretion dynamics in 12h day shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 2 (day shift) | 
| Melatonin secretion dynamics in 12h day shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 2 (day shift) | 
| Melatonin secretion dynamics in 12h night shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 8 (night shift) | 
| Melatonin secretion dynamics in 12h night shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 8 (night shift) | 
| Melatonin secretion dynamics in 12h night shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 8 (night shift) | 
| Melatonin secretion dynamics in 12h night shift | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 8 (night shift) | 
| Melatonin secretion dynamics at rest | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 13 (rest) | 
| Melatonin secretion dynamics at rest | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 13 (rest) | 
| Melatonin secretion dynamics at rest | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 13 (rest) | 
| Melatonin secretion dynamics at rest | Secretion of melatonin on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 13 (rest) | 
| Cortisol secretion dynamics in 12h day shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 2 (day shift) | 
| Cortisol secretion dynamics in 12h day shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 2 (day shift) | 
| Cortisol secretion dynamics in 12h day shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 2 (day shift) | 
| Cortisol secretion dynamics in 12h day shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 2 (day shift) | 
| Cortisol secretion dynamics in 12h night shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 8 (night shift) | 
| Cortisol secretion dynamics in 12h night shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 8 (night shift) | 
| Cortisol secretion dynamics in 12h night shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 8 (night shift) | 
| Cortisol secretion dynamics in 12h night shift | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 8 (night shift) | 
| Cortisol secretion dynamics at rest | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of total excretion (ng) | at day 13 (rest) | 
| Cortisol secretion dynamics at rest | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of acrophase (h) | at day 13 (rest) | 
| Cortisol secretion dynamics at rest | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of amplitude (ng) | at day 13 (rest) | 
| Cortisol secretion dynamics at rest | Secretion of cortisol on sequential urinary specimens collected every 4 or 8 hours. Measure of mesor (ng) | at day 13 (rest) | 
| Objective sleep quality | Measure of sleep latency assessed by sleep log | 15 days | 
| Objective sleep quality | Measure of sleep latency assessed by actigraphy | 15 days | 
| Objective sleep quality | Measure of sleep efficiency = total sleep / bedtime assessed by sleep log | 15 days | 
| Objective sleep quality | Measure of sleep efficiency = total sleep / bedtime assessed by actigraphy | 15 days | 
| Objective sleep quality | Measure of fragmentation index assessed by sleep log | 15 days | 
| Objective sleep quality | Measure of fragmentation index assessed by actigraphy | 15 days | 
| Objective sleep quality | Measure of intra-sleep wakefulness assessed by sleep log | 15 days | 
| Objective sleep quality | Measure of intra-sleep wakefulness assessed by actigraphy | 15 days | 
| Objective sleep duration | duration of sleep assessed by actigraphy | 15 days | 
| Excessive daytime sleepiness | This outcome will be assessed by the Epworth sleepiness Scale | at day 1 | 
| Asthenia | This outcome will be assessed by the Pichot asthenia scale | at day 1 | 
| Insomnia severity | This outcome will be assessed by the Insomnia Severity Index | at day 1 | 
| Anxiety | This outcome will be assessed by the Hospital Anxiety and Depression scale | at day 1 | 
| Depression | This outcome will be assessed by the Hospital Anxiety and Depression scale | at day 1 | 
| Vigilance at awakening | This outcome will be assessed by the Karolinska scale | at day 2, 8 and 13 | 
| Sleep subjective quality | This outcome will be assessed by the St Mary Hospital Questionary | at day 2, 8 and 13 | 
| Chronotype | This outcome will be assessed by the Horne and Ostberg Questionary | at day 1 | 
| Light exposition | This outcome will be assessed by the actigraphy | 15 days | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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shift work, melatonin, sleep