Scheduled afternoon-evening sleep leads to better night shift performance in older adults.

OBJECTIVES: This study investigated whether an intervention designed to reduce homeostatic sleep pressure would improve night shift performance and alertness in older adults. METHODS: Non-shift workers aged 57.9±4.6 (mean±SD) worked four day (07:00-15:00) and four night shifts (23:00-07:00). Two intervention groups were instructed to remain awake until ~13:00 after each night shift: the sleep timing group (ST; n=9) was instructed to spend 8 hours in bed attempting sleep, and the sleep ad-lib group (n=9) was given no further sleep instructions. A control group (n=9) from our previous study was not given any sleep instructions. Hourly Karolinska Sleepiness Scales and Psychomotor Vigilance Tasks assessed subjective sleepiness and performance. RESULTS: The ST group maintained their day shift sleep durations on night shifts, whereas the control group slept less. The ST group were able to maintain stable performance and alertness across the initial part of the night shift, while the control group's alertness and performance declined across the entire night. Wake duration before a night shift negatively impacted sustained attention and self-reported sleepiness but not reaction time, whereas sleep duration before a night shift affected reaction time and ability to sustain attention but not self-reported sleepiness. CONCLUSIONS: A behavioural change under the control of the individual worker, spending 8 hours in bed and waking close to the start of the night shift, allowed participants to acquire more sleep and improved performance on the night shift in older adults. Both sleep duration and timing are important factors for night shift performance and self-reported sleepiness.

Evaluation of sleep strategies between night shifts in actual shift workers.

OBJECTIVES: The aim of this observational study was to examine sleep obtained between consecutive night shifts from shift workers in their natural environment. The goal was to identify the various sleep strategies and the timing, duration, regularity, and quality of sleep associated with the strategies. METHODS: Participants (N = 33, 23 women, aged 40 ± 15years) reported their sleep information in daily diaries over 2weeks while working at least one series of consecutive night shifts. Sleep timing, duration, quality, and regularity were calculated for each sleep episode between consecutive night shifts. RESULTS: Based on the reported sleep behavior, shift workers were categorized as either morning, delayed, split- or mixed sleepers. We found significant differences between the groups in timing of sleep, feeling refreshed, and regularity of sleep between consecutive night shifts, whereas duration and subjective soundness of sleep did not show significant differences. CONCLUSIONS: In this sample, four sleep strategies were observed between consecutive night shifts in actual shift workers. These observations may help design future interventions to improve sleep that are individualized to the worker.

Feasibility, effectiveness, and acceptability of an afternoon-evening sleep schedule in older nightshift workers.

Study Objectives: To explore the feasibility, effectiveness, and acceptability of an afternoon-evening sleep schedule in older (age 50-65 years) nightshift workers. Methods: We used a three-part strategy: a screening survey to identify individuals who said they could adopt an 8-hour afternoon-evening sleep schedule; a field study where daily diary and actigraphy data were collected during a baseline week and intervention week, with randomization to self-selected sleep, 8-hour afternoon-evening time in bed (TIB), or 8-hour self-selected TIB; and follow-up focus groups to understand the acceptability of the intervention. Results: Gender (p < 0.001), Hispanic ethnicity (p = 0.023), the care of children (p = 0.014), and chronotype (p = 0.012), predicted the reported ability to spend 8 hours in bed in the afternoon-evening. Participants assigned to the 8-hour self-selected and 8-hour afternoon-evening groups significantly increased their TIB and sleep duration compared to baseline (p < 0.05), while the control group did not. Although spending 8 hours in bed was feasible for the participants during the study, focus group discussions indicated participants would not continue an 8-hour TIB schedule after the study due to family responsibilities and other activities of daily living. Conclusions: Spending 8 hours in bed between successive night shifts, initiated at both a self-selected time and in the afternoon-evening, increased the sleep duration of older shiftworkers, but most would not continue such a schedule on their own. Additional research is needed to find countermeasures for the reduced sleep duration experienced by most shiftworkers that are not only effective, but also compatible with shiftworkers' lifestyles.