Quick Returns - Sleep, Cognitive Functions and Individual Differences

Quick Returns - Sleep, Cognitive Functions and Individual Differences: An Experimental Approach

The project will contribute with new knowledge concerning how short rest periods between two consecutive shifts (<11h, often defined as a Quick Return (QR)) affects sleep and cognitive performance. The study will further examine whether individual differences in personality traits and genotypes may explain individual differences in performance and sleep. Data will be collected with a randomized cross-over design, in an experimental laboratory setting.

Rotating shift workers may have a narrow time window to rest after an evening shift, before returning early to work for a day shift. In the literature, a rest opportunity of less than 11 hours between two consecutive shifts, is defined as a Quick Return (QR). Most often, this is occurs when working an evening shift followed by a day shift. Survey- and longitudinal studies have found associations between QRs and an increased risk of being involved in occupational accidents. However, no studies have experimentally investigated how a QR scenario may affect performance at work and sleep between the two shifts. Thus, the project will experimentally simulate QRs, where a battery of cognitive tests will be administered in a laboratory to indicate performance. Objective and subjective sleep will be measured/reported at home where participants normally sleep. Additionally, genotype- and personality trait data will be collected and used as moderators in the analyses.

A randomized cross-over design with two groups will be applied. In one condition, participants will work an evening shift (03:00PM-11:00PM) followed by a day shift (07:00AM-03:00PM, QR). In the other condition, participants work a day shift (07:00AM-03:00PM) followed by another day shift. Four weeks later after being in one of the conditions, the participants will return to the laboratory and work in the opposite condition. Sleep will be subjectively reported with a sleep diary and objectively measured using a low-powered ultra-wideband radar, two days before and between the two simulated shifts in each of the two conditions.

Inclusion Criteria:

• Participants are physically and mentally healthy (assessed with BMI and 'General Health Questionnaire-12)'.
• Participants accept to comply to the protocol (retain regular bed- and wake times before the simulated shifts).
• Refrain from alcohol and maintain regular nicotine and caffeine usage during participation.
• Norwegian as primary language/proficiency in Norwegian language.

Exclusion Criteria:

• Neurological, psychiatric or sleep related disorders ('Bergen Insomnia Scale, 'Global sleep assessment questionnaire').
• Extreme 'morning-eveningness' type ('Horne-Östberg).
• Use of medication that affect sleep or cognitive performance.
• Pregnancy.