With cannabis laws rapidly changing, there’s an interest in whether it affects work performance —before, during, or after work. While cannabis may be legalized in your state, some employers still hold the right to ban employees from consuming it through regular drug tests.
A 2020 study sought to discover if these measures are warranted and if cannabis has any impact on work performance.  The study differentiated itself from others by distinguishing when cannabis was used (before, during, or after work) versus a blanket question of “have you used cannabis within the past six months”. Researchers observed 281 employees along with their direct supervisors. Through these observations, they focused on three points of interest: task performance (e.g., completing assigned duties, meeting requirements), organizational citizenship behavior (OCB), and two forms of counterproductive work behaviors (CWB). Employee supervisors evaluated work performance.
While responsibilities differ from job to job, most employees have met or are accountable for tasks, OCB, and productive behavior upon hiring. With that said, the question is whether cannabis falters or improves performance in these domains. Employees self-reported their cannabis use.
In the case of task performance, the researchers note that most previous studies found a mix (positive and negative) of results. However, they theorize that the reason for this is these studies never observed when cannabis was consumed.
Their research concluded that when one consumes cannabis prior to or during work, there may be negative effects on task performance. The authors suggest that cannabis may impair certain forms of cognitive functioning and, in turn, make it more difficult to complete certain tasks. Yet, the researchers found that those who consume cannabis after work saw no negative nor positive effects on their task performance.
Beyond task performance, it’s important for employees to have some sense of OCB. Traits of this category include “informal, spontaneous, volitional behaviors that help the organization or people within the organization.” The study hypothesizes and concludes that cannabis use before or during work correlates to negative effects on citizenship behavior toward the organization. Interestingly, the study suggests that employees using cannabis at work might not notice when colleagues need assistance or be able to shift attention from their own tasks to those of others which could be interpreted as a focused mindset. The study hypothesizes that individuals using cannabis after work are “likely less focused on troublesome aspects of their lives” which, in turn, enables them to devote more resources and energy once back at work. However, cannabis use at any time was not correlated to OCB toward individuals within the organization.
According to the study, cannabis use can also influence CWB. These include actions that harm a company in terms of production and property deviance, namely “fantasizing or daydreaming,” and “took property from work without permission.”
While correlation with some of the hypotheses was proposed, it’s important to review the study’s limitations which include social media recruitment, self-reported and supervisor-reported data, and the lack of “within-person” or crossover data to determine what actually caused the correlations. The nature of the work performed was also not noted or controlled.  Not all forms of cannabis use harmed work performance, which the authors state is “contrary to commonly held assumptions.” As with any study, it’s important to understand and incorporate as many of the nuances as possible versus jumping to conclusions based on speculative correlations.
References Bernerth JB, Walker JH. Altered states or much to do about nothing? A study of when cannabis is used in relation to the impact it has on performance. SAGE Journal. 2020;45(4): 459-478. [Impact Factor: 0.715; Times Cited: n/a]