Light Intervention for Adaptation to Night Work

NCT03203538 | Completed

• 1 other identifier: 270755
• Study Type: interventional
• Target: 97
• Locations: 1 country
• Sites: 1

Brief Summary

The project will contribute with new knowledge concerning how aspects of the physical work environment (lighting conditions) can be arranged to facilitate the workers' adaptation to night work. This is important given the reported adverse consequences of shift work for performance, safety, and health. The project involves a series of three experimental, laboratory based shift work simulation studies. The aim is to investigate how different lighting conditions (intensities and colour temperature), administered through light emitting diode (LED) based bright light integrated standard room lighting, affects adaptation to three consecutive simulated night shifts and re adaptation to a day oriented schedule on measures of alertness, cognitive performance, sleep and circadian rhythm. The proposed project examines the effects of interventions that can be applied in naturalistic settings and will be based on new laboratory infrastructure available at the laboratories situated in the Faculty of Psychology, University of Bergen.

Conditions

Shift-Work Related Sleep Disturbance; Sleep Deprivation; Sleep

Keywords

night work; shift work; light; bright light; sleep; cognitive performance; circadian rhythm

Outcome Measures

Primary Outcomes (3)

• Cognitive performance

  Cognitive performance will be measured using the Psychomotor Vigilance Test (PVT). The PVT measures sustained attention, and is considered the 'gold standard' for assessing the effects of sleep deprivation on cognition. The task will be performed approx. every 1.5h throughout the nightshifts.

  3 nights

• Circadian phase

  Circadian phase will be measured through assessement of 'Dim Light Melatonin Onset' (DLMO). Saliva samples will be collected every hour in the evening (from 7 pm) to one hour past regular bedtime, one day before the first night shift and the day after the night shift period. Saliva will be analyzed for melatonin, giving an estimate on DLMO.

  5 days-nights

• Sleep

  Sleep will be measured objectively using actigraphy

  9 days-nights

Secondary Outcomes (25)

• Subjective sleepiness

  3 nights

• Self-reported sleep

  9 days-nights

• Heart rate variability

  3 nights

• Interleukin

  3 nights

• Granulocyte macrophage colony-stimulating factor (GM-CSF)

  3 nights

Study Arms (6)

Light intensity, 1000 lux (4000 K)

EXPERIMENTAL

Participants will work three consecutive simulated night shifts under full-spectrum LED-light, 1000 lux (4000 Kelvin) administered through standard room lighting.

Device: LED-light, 1000 lux

Light intensity, 100 lux (4000 K)

ACTIVE COMPARATOR

Participants will work three consecutive simulated night shifts under full-spectrum LED-light, 100 lux (4000 Kelvin) administered through standard room lighting.

Device: LED-light, 100 lux

Colour temperature, 7000 Kelvin

EXPERIMENTAL

Participants will work three consecutive simulated night shifts under full-spectrum LED-light, 7000 K (200 lux) administered through standard room lighting.

Device: LED-light, 7000 K

Colour temperature, 2500 Kelvin

ACTIVE COMPARATOR

Participants will work three consecutive simulated night shifts under full-spectrum LED-light, 2500 K (200 lux) administered through standard room lighting.

Device: LED-light, 2500 K

Blue light, 455 nm

EXPERIMENTAL

Participants work one night shift with blue LED-light (peak wavelength 455 nm) administered through standard room lighting.

Device: Blue LED-light

Red light, 615 nm

ACTIVE COMPARATOR

Participants work one night shift with red LED-light (peak wavelength 615 nm) administered through standard room lighting.

Device: Red LED-light

Interventions

LED-light, 1000 lux DEVICE

Full-spectrum light, 1000 lux, 4000 K. Represent a light intensity within acceptable range (light that is not too glary); 4000 K is among the most commonly used indoor light colour temperatures.

Light intensity, 1000 lux (4000 K)

LED-light, 100 lux DEVICE

Full-spectrum light, 100 lux, 4000 K. Represent a light intensity within acceptable range (light that provides sufficient eye sight); 4000 K is among the most commonly used indoor light colour temperatures.

Light intensity, 100 lux (4000 K)

LED-light, 7000 K DEVICE

Full-spectrum light, 7000 K, 200 lux. Represent the upper border of common colour indoor light temperature, 200 lux is a common indoor light intensity.

Colour temperature, 7000 Kelvin

LED-light, 2500 K DEVICE

Full-spectrum light, 2500 K, 200 lux. Represent the lower border of common colour indoor light temperature, 200 lux is a common indoor light intensity.

Colour temperature, 2500 Kelvin

Blue LED-light DEVICE

Blue light with peak wavelength 455 nm. Known to delay the circadian rhythm, suppress melatonin, and increase alertness.

Blue light, 455 nm

Red LED-light DEVICE

Red light with peak wavelength 615 nm. Known not to affect the circadian rhythm, melatonin, and alertness.

Red light, 615 nm

Eligibility Criteria

• Age: 19 Years - 30 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• Participants are physical and mentally healthy (assessed with BMI and 'General Health Questionnaire-12')
• Participants accept to comply with the protocol (refrain from alcohol, tobacco and coffee, and retain regular bed- and wake-times the week before the simulated night shifts)

You may not qualify if:

• Neurological, psychiatric or sleep related disorders ('Bergen Insomnia Scale', 'global sleep assessement questionnaire')
• Extreme 'morningness-eveningness' type ('Horne Östberg morningness eveningness questionnaire')
• Use of medication
• Worked night shifts the last 3 months
• Travelled through more than two time zones the last 3 months

Sponsors & Collaborators

• University of Bergen: lead
• Glamox: collaborator

Study Sites (1)

The faculty of psychology, University of Bergen

Bergen, Hordaland, 5020, Norway

Location

Related Publications (5)

• Sunde E, Harris A, Olsen OK, Pallesen S. Moral decision-making at night and the impact of night work with blue-enriched white light or warm white light: a counterbalanced crossover study. Ann Med. 2024 Dec;56(1):2331054. doi: 10.1080/07853890.2024.2331054. Epub 2024 Apr 18.

  PMID: 38635448 DERIVED

• Sunde E, Mrdalj J, Pedersen TT, Bjorvatn B, Gronli J, Harris A, Waage S, Pallesen S. Bright light exposure during simulated night work improves cognitive flexibility. Chronobiol Int. 2022 Jul;39(7):948-963. doi: 10.1080/07420528.2022.2050922. Epub 2022 Mar 28.

  PMID: 35343353 DERIVED

• Sunde E, Pedersen T, Mrdalj J, Thun E, Gronli J, Harris A, Bjorvatn B, Waage S, Skene DJ, Pallesen S. Alerting and Circadian Effects of Short-Wavelength vs. Long-Wavelength Narrow-Bandwidth Light during a Simulated Night Shift. Clocks Sleep. 2020 Nov 25;2(4):502-522. doi: 10.3390/clockssleep2040037.

  PMID: 33255613 DERIVED

• Sunde E, Pedersen T, Mrdalj J, Thun E, Gronli J, Harris A, Bjorvatn B, Waage S, Skene DJ, Pallesen S. Blue-Enriched White Light Improves Performance but Not Subjective Alertness and Circadian Adaptation During Three Consecutive Simulated Night Shifts. Front Psychol. 2020 Aug 18;11:2172. doi: 10.3389/fpsyg.2020.02172. eCollection 2020.

  PMID: 33013558 DERIVED

• Sunde E, Mrdalj J, Pedersen T, Thun E, Bjorvatn B, Gronli J, Harris A, Waage S, Pallesen S. Role of nocturnal light intensity on adaptation to three consecutive night shifts: a counterbalanced crossover study. Occup Environ Med. 2020 Apr;77(4):249-255. doi: 10.1136/oemed-2019-106049. Epub 2020 Feb 4.

  PMID: 32019847 DERIVED

MeSH Terms

Conditions

Sleep Deprivation

Condition Hierarchy (Ancestors)

Dyssomnias; Sleep Wake Disorders; Nervous System Diseases; Neurologic Manifestations; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Mental Disorders

Study Officials

• Erlend Sunde

  University of Bergen, department of psychosocial science

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Masking Details: Participants will not be given information on the hypotheses/ expected effects from the different interventions (light conditions).
• Purpose: SUPPORTIVE CARE
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Three related night shift studies have been planned. Each study investigates how different lighting conditions, administered through LED-based bright light integrated standard room lighting, affects adaptation to simulated night shifts and re adaptation to a day oriented schedule. In each study, 28 participants (84 in total) will be exposed to the interventions (light conditions) in a randomized, blinded, controlled, crossover study. The simulated night shifts will last from 11pm to 7am. The specific light conditions will last from 11pm to 5am (study 1: 1000 lux vs. 100 lux; study 2: 7000 K vs. 2500 K; study 3: 455 nm vs. 615 nm) where after (from 5am to 7am) all participants will be exposed to the same light conditions (200 lux, 4000 K). After completion of one bout of night work (three consecutive shifts for study 1 and 2; one night shift for study 3) there will be a washout period of four weeks before the participants cross over.

Study Record Dates

• First Submitted: May 3, 2017
• First Posted: June 29, 2017
• Study Start: August 25, 2017
• Primary Completion: March 27, 2019
• Study Completion: March 27, 2019
• Last Updated: May 16, 2019

Record last verified: 2018-02

Data Sharing

• IPD Sharing: Will not share

Locations

NO (1)