Effects of Morningness on Night Split Shift Performance

The goal is to investigate if the morningness-eveningness dimension mediates sleep and function on spilt night shifts (midnight-4am and 4am-8am).

Does those with high score of morningness function relatively better on the last compared to the first split shift?

Participants will:

Record their sleep from 2 days prior to 2 days following the split shift During the shifts complete questionnaires assessing mood, sleepiness and perceived performance as well as complete cognitive tests: Psychomotor vigilance test, digit symbol substitution test, working memory scanning test, reversal learning test, and visual search test

Study Overview

• Status: Active, not recruiting
• Conditions: Shift-work Disorder
• Intervention / Treatment: Behavioral: Time of night shift

Detailed Description

A sample of 28 students will be recruited and exposed to two conditions in a randomized, controlled, crossover study. They will be assessed with subjective (sleep diary) and objective sleep measures (sleep radar) for 2 days before the night shift, during the night shift and 2 days following the night shift. The simulated night shifts will last from midnight to 8am and will be divided into two halves (midnight-4am and 4am-8am), denoted as split-shift, and for each participant separated by at least 1 week. Based on the Horne-Östberg Morningness-Eveningness Questionnaire (median spilt) two groups are created, from which participants will be randomized to the two orders of the spilt-shift.

Each hour on each shift the participants will complete: Positive and Negative Affect Schedule (PANAS), Karolinska Sleepiness Scale, perceived performance and the following cognitive tests: Psychomotor vigilance test, Digit symbol substitution test, Working memory scanning test, Reversal learning test, and Visual search test.

Data will be analyzed with linear mixed models with three fixed factors: Group (low vs. high morningness), shift (midnight-4am vs. 4am-8am), and hour and one random factor (participant).

• Study Type: Interventional
• Enrollment (Estimated): 30
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Norway
  • Bergen, Norway, 5020
    • University of Bergen

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• 18-40 years old
• no incorrectable vision problems

Exclusion Criteria:

* regular use of sleep medication

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Late night shift (4am - 8am)	Behavioral: Time of night shift; Early vs. late night split night shift
Active Comparator: Early night shift (midnight-4am)	Behavioral: Time of night shift; Early vs. late night split night shift

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Total sleep time	Total sleep (sleep diary and radar). Higher values indicates more sleep	Total sleep time between 6pm day before shift start to 6pm the day the shift end for both early night shift (midnight-04am) and late night shift (04am-08am)
Psychomotor Vigilance Test (PVT)	Reaction time (mean 1/RT) and number of lapses (RTs≥500 ms). For mean 1/RT higher values are associated with best performance, on lapses higher values are associated with worst performance	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Karolinska Sleepiness Scale (KSS)	Assessment of state sleepiness, range 1-9 (higher scores indicate worse state)	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Sleep efficiency (percentage of time in bed one sleeps)	Sleep efficiency (diary and radar). Range from 0-100%. Higher scores indicate best state	Between 6pm day before shift start to 6pm the day the shift end for both early night shift (midnight-04am) and late night shift (04am-08am)
Digital Symbol Substitution Test	Test where one match symbols to numbers as fast as possible. Range 0-100. Higher scores indicate best performance	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Positive and Negative Affect Schedule (PANAS)	Assessment of mood/affect. Range 10-50. On positive mood subscale higher scores indicate best state, on negative mood state, higher scores indicate worst state	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Self-rated performance	Self-rated performance on cognitive tests. Range 1-10. Higher scores indicate best performance rating	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Working Memory Scanning Test (probed recall)	Test presenting list of words. Then words are presented and subjects decide if word was present or not in list presented. The accuracy and RTs for positive trials (where probe was present in list) will be used as dependent variables. Higher accuracy and lower reaction time are associated with best performance	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Reversal Learning Test	Test measuring the ability to differentiating between "go-stimuli" and "no-go stimuli" before and after reversal of go and no-go stimuli. Discriminability (hit rate/false alarm rate) and response bias before and after reversal are recorded. Higher discriminability indicates better performance, higher response bias indicate worse performance	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)
Visual Search Test	Multiple objects are presented, and from among them a target is identified. The task of the subject is finding the target. Outcomes are reaction time (RT) and accuracy. Lower reaction times and higher accuracy are associated with best performance	Hourly during shifts (0:15am, 1:15am, 2:15am and 3:15am on early night shift; 4:15am, 5:15am, 6:15am and 7:15 am on late night shift)

Collaborators and Investigators

• Sponsor: University of Bergen

Study record dates

Study Major Dates

• Study Start (Actual): April 19, 2024
• Primary Completion (Estimated): June 20, 2024
• Study Completion (Estimated): December 31, 2024

Study Registration Dates

• First Submitted: May 14, 2024
• First Submitted That Met QC Criteria: May 30, 2024
• First Posted (Actual): June 3, 2024

Study Record Updates

• Last Update Posted (Actual): June 13, 2024
• Last Update Submitted That Met QC Criteria: June 12, 2024
• Last Verified: June 1, 2024

More Information

Terms related to this study

• Other Study ID Numbers: M3447

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED
• IPD Plan Description: If legel in terms of data protection regulations data will be shared

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No