Simulated Night Shift for Circadian Rhythm Disorder

(SPOTLIGHT Trial)

Recruiting in Aurora (>99 mi)

Overseen By Arpi Bocchieriyan, BS

Age: 18 - 65

Sex: Any

Trial Phase: Academic

Sponsor: University of Colorado, Denver

Must be taking: Oral contraceptives

Must not be taking: Antidepressants, Neuroleptics, Tranquilizers, others

Disqualifiers: Obesity, Smoking, Psychiatric disorders, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: Unknown

20 Participants Needed

Trial Summary

What is the purpose of this trial?

This trial will test if working night shifts affects bone health by increasing stress levels. It will also check if returning to a normal sleep schedule can reverse any negative effects.

Will I have to stop taking my current medications?

The trial requires participants to stop using medications that affect bone turnover or sleep, such as glucocorticoids, osteoporosis medications, and sleep medications, at least one month before the study. If you are on these medications, you may need to stop taking them to participate.

What data supports the effectiveness of the treatment Simulated Night Shift Work for Circadian Rhythm Disorder?

Research suggests that adjusting light exposure and sleep schedules can help align the body's internal clock with night shift work, improving sleep quality and reducing fatigue. This approach, known as circadian adaptation, has been shown to help night shift workers better adjust to their schedules, potentially improving their overall health and safety. ^{1 2 3 4 5}

Is simulated night shift work generally safe for humans?

Simulated night shift work can lead to increased crash risk during morning commutes, disturbed sleep, and health issues like cardiovascular risk and sleep disorders. These effects are due to the disruption of the body's natural sleep-wake cycle, which can cause excessive sleepiness and reduced alertness. ^{6 7 8 9 10}

How does the Simulated Night Shift treatment differ from other treatments for circadian rhythm disorder?

The Simulated Night Shift treatment is unique because it uses controlled light and dark cycles to help adjust the body's internal clock to align with night work and day sleep schedules, unlike other treatments that might focus on medication or lifestyle changes. ^{1 5 11 12 13}

Research Team

Christine M Swanson, MD, PhD

Principal Investigator

CU Anschutz

Eligibility Criteria

Healthy adults aged 20-40, who sleep 7-9 hours at night and are fully vaccinated against COVID-19. Women must be premenopausal, on oral contraception, not breastfeeding. Participants should commit to a study including inpatient stays and wear a wrist monitor for activity tracking.

Inclusion Criteria

I am a premenopausal woman not breastfeeding and on birth control pills.

Willing and able to complete a sleep diary, wear a wrist actigraphy monitor and complete a 3-6 week research study including two 4-night inpatient stays.

Willing and able to complete a sleep diary, wear a wrist actigraphy monitor and complete a 3-6 week research study including two 4-night inpatient stays

Exclusion Criteria

You have smoked within the past year.

Your bone density is very low compared to the average for your age and gender.

Your vitamin D level is less than 20 ng/mL.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Baseline

Participants undergo baseline measurements and sleep under normal conditions

1 night

Inpatient stay

Simulated Night Shift Work

Participants experience simulated night shift work with 3-hour afternoon naps and 12-hour night shifts

3 nights

Inpatient stay

Follow-up

Participants are monitored for changes in bone turnover markers after resuming normal sleep patterns

4 weeks

Treatment Details

Interventions

• Simulated short term night shift work

Trial Overview The trial is testing how simulated night shift work affects bone metabolism by measuring bone turnover markers and sympathetic nervous system tone. It involves two sets of four-night inpatient stays with follow-up to see if normal patterns reverse any changes.

Participant Groups

Group I: Simulated Night Shift Work Experimental Treatment 1 Intervention

Two inpatient stays, each involving a baseline night, followed by a 3-hour afternoon nap opportunity, and then three 12-hour night shifts, with 8-hour daytime sleep opportunity in between.

Group II: Control (8 hours nocturnal sleep) Active Control 1 Intervention

Inpatient protocol involves 8-hour sleep opportunity during the biological night throughout.

Who Is Running the Clinical Trial?

University of Colorado, Denver

Lead Sponsor

Trials

1,842

Recruited

3,028,000+

National Heart, Lung, and Blood Institute (NHLBI)

Collaborator

Trials

3,987

Recruited

47,860,000+

Findings from Research

Shift work disorder affects 15 to 25% of the U.S. labor force, leading to significant disruptions in sleep patterns and overall health due to misalignment with the body's circadian rhythm.

Clinicians require better understanding of the circadian rhythm's impact on human functioning and the consequences of shift work disorder to improve diagnosis and treatment in affected individuals.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

How the circadian rhythm affects sleep, wakefulness, and overall health: background for understanding shift work disorder. Krystal, AD.[2012]

A study on simulated shift work showed that adjusting sleep/dark schedules can help shift workers adapt by inducing phase shifts in their circadian rhythms, although these shifts may not fully align with night shift demands.

The findings suggest that while scheduled sleep can improve adaptation for night shift workers, the extent of the phase shifts achieved may still leave some workers struggling with sleep quality and timing.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Scheduling of sleep/darkness affects the circadian phase of night shift workers. Santhi, N., Duffy, JF., Horowitz, TS., et al.[2013]

A systematic review of 68 studies on interventions for shiftworkers found that only 60.3% assessed implementation, highlighting a gap in understanding how these interventions are applied in real-world settings.

The average quality of implementation assessment was moderate (2.56 out of 5), and only a small number of studies identified enablers (25%) or barriers (26.5%) to effective implementation, suggesting that future research should focus more on these aspects to improve intervention effectiveness.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Implementation of interventions designed to promote healthy sleep and circadian rhythms in shiftworkers. Harrison, EM., Schmied, EA., Yablonsky, AM., et al.[2021]

Hospitalists working night shifts face challenges due to misalignment with their natural circadian rhythms, leading to sleep deprivation and increased risk of medical errors.

Implementing circadian adaptation strategies, such as improving sleep hygiene, using caffeine, and exposure to bright light, can help mitigate fatigue and enhance safety for hospitalists, but further research is needed to optimize scheduling and performance.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Sleep and circadian misalignment for the hospitalist: a review. Schaefer, EW., Williams, MV., Zee, PC.[2015]

Night shift workers often struggle to adjust their circadian rhythms, which can negatively impact their health and safety; this paper reviews studies that used artificial light to help shift these rhythms for better adaptation.

The authors provide fundamental principles and a specific example of a light/dark schedule that can help night shift workers align their circadian rhythms with their unusual work hours, potentially improving their quality of life.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

How to use light and dark to produce circadian adaptation to night shift work. Eastman, CI., Martin, SK.[2019]

Working multiple consecutive night shifts significantly increases the risk of crashes during the morning commute, with crash likelihood being 11 times higher at the start of the week compared to pre-work commutes.

Although crash risk is highest at the beginning of the week, it decreases over the course of the week, indicating that fatigue effects may lessen as the body adjusts to the night shift schedule.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The likelihood of crashing during a simulated post-work commute decreases across a week of consecutive night shifts. Roach, GD., Sach, EJ., Reiter, AM., et al.[2021]

Exposure to daylight when night shift nurses drive home can disrupt their circadian rhythms, leading to increased health risks and decreased job performance.

Shifts from 3:00 a.m. to 3:00 p.m. and 3:00 p.m. to 3:00 a.m. are associated with less physiological and emotional stress, suggesting that awareness and management of circadian rhythms could improve nurses' health and patient care quality.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Understanding circadian rhythms: a holistic approach to nurses and shift work. Efinger, J., Nelson, LC., Starr, JM.[2018]

Shift work affects nearly 20% of the global labor force and is linked to negative impacts on worker health, safety, and quality of life due to disruptions in circadian rhythms and increased sleepiness during shifts.

Management strategies for shift work disorder (SWD) include promoting better sleep and wakefulness, but more research is needed to understand the health risks and develop effective treatments for those affected.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Shift work and the assessment and management of shift work disorder (SWD). Wright, KP., Bogan, RK., Wyatt, JK.[2022]

A study of 59 Italian orthopaedic nurses revealed that those working night shifts had significantly lower rest-activity circadian rhythm amplitudes compared to day shift nurses, indicating disrupted circadian rhythms (p < 0.001).

Both normal weight and overweight night shift nurses exhibited reduced amplitude in their circadian rhythms during work hours, suggesting that shift work negatively impacts health regardless of body weight (p < 0.01 for normal weight and p < 0.001 for overweight).

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effects of Shift Work in a Sample of Italian Nurses: Analysis of Rest-Activity Circadian Rhythm. Galasso, L., Mulè, A., Castelli, L., et al.[2021]

Shift work affects 15-30% of adult workers, leading to a condition known as shift work sleep disorder, which can cause excessive sleepiness and sleep disruption in 2-5% of these workers.

The disorder significantly impacts worker safety and performance, increasing the risk of accidents and impairing health, particularly during night shifts when sleepiness is at its peak.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Impacts of shift work on sleep and circadian rhythms. Boivin, DB., Boudreau, P.[2022]

Frequent shift rotation in employment can lead to specific sleep disorders, particularly Delayed Sleep Phase (DSP) insomnia, which disrupts circadian rhythms and impairs daily functions.

Shift work can also result in excessive daytime sleepiness disorders, such as narcolepsy, highlighting the need for clinicians to consider the impact of disrupted sleep-waking schedules on their patients.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Circadian rhythm disturbances and sleep disorders in shift workers. Guilleminault, C., Czeisler, C., Coleman, R., et al.[2015]

In a study involving 86 shift-worker nurses, taking 5 mg of melatonin 30 minutes before sleep significantly reduced the time it took to fall asleep compared to a placebo.

Melatonin did not affect the total sleep time and was found to have no adverse effects, suggesting it is a safe and effective option for improving sleep onset in night shift workers.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Efficacy and hypnotic effects of melatonin in shift-work nurses: double-blind, placebo-controlled crossover trial. Sadeghniiat-Haghighi, K., Aminian, O., Pouryaghoub, G., et al.[2020]

Shift workers, particularly those with an evening chronotype, are at a higher risk for developing obesity and other chronic health issues due to circadian misalignment, even when accounting for short sleep duration.

This review of 21 studies highlights the need for further research on how aligning shift work schedules with individual chronotypes could improve health outcomes for shift workers, suggesting potential strategies for occupational health interventions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Identifying shift worker chronotype: implications for health. Hittle, BM., Gillespie, GL.[2019]

References

1. United States pubmed.ncbi.nlm.nih.gov

How the circadian rhythm affects sleep, wakefulness, and overall health: background for understanding shift work disorder. [2012]

2. Ireland pubmed.ncbi.nlm.nih.gov

Scheduling of sleep/darkness affects the circadian phase of night shift workers. [2013]

3. England pubmed.ncbi.nlm.nih.gov

Implementation of interventions designed to promote healthy sleep and circadian rhythms in shiftworkers. [2021]

4. United States pubmed.ncbi.nlm.nih.gov

Sleep and circadian misalignment for the hospitalist: a review. [2015]

5. England pubmed.ncbi.nlm.nih.gov

How to use light and dark to produce circadian adaptation to night shift work. [2019]

6. England pubmed.ncbi.nlm.nih.gov

The likelihood of crashing during a simulated post-work commute decreases across a week of consecutive night shifts. [2021]

7. United States pubmed.ncbi.nlm.nih.gov

Understanding circadian rhythms: a holistic approach to nurses and shift work. [2018]

8. England pubmed.ncbi.nlm.nih.gov

Shift work and the assessment and management of shift work disorder (SWD). [2022]

9. Switzerland pubmed.ncbi.nlm.nih.gov

Effects of Shift Work in a Sample of Italian Nurses: Analysis of Rest-Activity Circadian Rhythm. [2021]

10. France pubmed.ncbi.nlm.nih.gov

Impacts of shift work on sleep and circadian rhythms. [2022]

11. Netherlands pubmed.ncbi.nlm.nih.gov

Circadian rhythm disturbances and sleep disorders in shift workers. [2015]

12. England pubmed.ncbi.nlm.nih.gov

Efficacy and hypnotic effects of melatonin in shift-work nurses: double-blind, placebo-controlled crossover trial. [2020]

13. Japan pubmed.ncbi.nlm.nih.gov

Identifying shift worker chronotype: implications for health. [2019]