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. 2017 Sep 1;178:534-543.
doi: 10.1016/j.drugalcdep.2017.04.036. Epub 2017 Jun 28.

Smoked Marijuana Attenuates Performance and Mood Disruptions During Simulated Night Shift Work

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Smoked Marijuana Attenuates Performance and Mood Disruptions During Simulated Night Shift Work

Diana R Keith et al. Drug Alcohol Depend. .
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Abstract

Individuals who work nonstandard schedules, such as rotating or night shifts, are more susceptible to workplace injuries, performance decrements, and reduced productivity. This population is also almost twice as likely to use illicit drugs as individuals working a standard day shift. The purpose of this study was to examine the effects of smoked marijuana on performance, mood, and sleep during simulated shift work. Ten experienced marijuana smokers completed this 23-day, within-participant residential study. They smoked a single marijuana cigarette (0, 1.9, 3.56% Δ9-THC) one hour after waking for three consecutive days under two shift conditions: day shift and night shift. Shifts alternated three times during the study, and shift conditions were separated by an 'off' day. When participants smoked placebo cigarettes, psychomotor performance and subjective-effect ratings were altered during the night shift compared to the day shift: performance (e.g., vigilance) and a few subjective ratings were decreased (e.g., "Self-Confident"), whereas other ratings were increased (e.g., "Tired"). Objective and subjective measures of sleep were also disrupted, but to a lesser extent. Marijuana attenuated some performance, mood, and sleep disruptions: participants performed better on vigilance tasks, reported being less miserable and tired and sleep a greater number of minutes. Limited negative effects of marijuana were noted. These data demonstrate that abrupt shift changes produce performance, mood, and sleep decrements during night shift work and that smoked marijuana containing low to moderate Δ9-THC concentrations can offset some of these effects in frequent marijuana smokers.

Keywords: Cannabis; Marijuana; Mood; Performance; Shift work; Sleep.

Conflict of interest statement

Author Disclosures

Conflict of Interest

We declare no competing interests.

Figures

Figure 1
Figure 1
Upper panel: AUC values for total trials (RA), total number of hits (RIT), and total number of digits entered as a function of shift condition and day within condition. §Significant difference between the day and night shift conditions for that day following placebo administration (p<0.05). Bottom panel: AUC values for total trials (RA), total number of hits (RIT), and total number of digits entered as a function of Δ9-THC concentration and day of the night shift condition. *Significant difference between placebo and Δ9-THC concentration for that day (p<0.05). #Significant difference between 1.9 and 3.56% Δ9-THC for that day (p<0.05). Error bars represent 1 SEM. Overlapping error bars were omitted for clarity.
Figure 2
Figure 2
Upper panel: AUC values for visual analog scale ratings of 'Self-Confident,' 'Tired,' and 'Miserable' as a function of shift condition and day within condition. §Significant difference between the day and night shift conditions for that day following placebo administration (p<0.05). Bottom panel: AUC values for visual analog scale ratings of 'Self-Confident,' 'Tired,' and 'Miserable' as a function of Δ9-THC concentration and day of the night shift condition. *Significant difference between placebo and Δ9-THC concentration for that day (p<0.05). Error bars represent one SEM. Overlapping error bars were omitted for clarity.
Figure 3
Figure 3
Upper panel: Total sleep time from the previous evening as measured by the Nightcap and selected mean subjective effects from the sleep questionnaire as a function of shift condition and day within condition. §Significant difference between the day- and night shift conditions for that day following placebo administration (p<0.05). Bottom panel: Total sleep time from the previous evening as measured by the Nightcap and selected mean subjective effects from the sleep questionnaire as a function of Δ9-THC concentration and day of the night shift condition. *Significant difference between placebo and Δ9-THC concentration for that day (p<0.05). #Significant difference between 1.9 and 3.56% Δ9-THC for that day (p<0.05). Error bars represent 1 SEM. Overlapping error bars were omitted for clarity.
Figure 4
Figure 4
The number of trials completed on the Repeated Acquisition Task (RA) as a function of Δ9-THC concentration and time on one night of the night-shift work period. Marijuana was administered at time point 0. Error bars represent 1 SEM. Overlapping error bars were omitted for clarity.

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