Does cannabis use after work affect a person's productivity?

The psychological effects of cannabis on the human body have been long-debated - and as a result of the drug’s legal status and its effects, it has been included as a prohibited substance in workplace drug policies for businesses across the UK. 

There are, however, those who maintain that usage outside of the workplace - in the evenings once the working day has finished, for example - has no impact on their ability to give 100% performance at work. 

In May 2020, journal Group & Organization Management published a paper entitled Altered States or Much to Do About Nothing? A Study of When Cannabis Is Used in Relation to the Impact It Has on Performance. The paper explored the relationship between the usage of different forms of cannabis and different elements of workplace performance, concluding that cannabis use after working hours did not impact on any of the measures of workplace performance. However, cannabis use before and after work, says the paper, predictably had an impact on an individual’s ability to perform certain tasks. 

Here, we explore the research in more detail - as well as the implication that it could have on UK drug testing programmes.

What does the research tell us? 

This research was conducted for two primary reasons: firstly, the lack of existing research into the temporal effects of cannabis usage, and secondly, the fact that, for research purposes, cannabis is often grouped with other substances for analysis purposes. The creators of the study argued that this should not be the case, as “cannabis effects dissipate relatively quickly with fewer residual effects than other substances”.  

In order to recruit participants for the study, the creators took two routes: sourcing full-time employees and their supervisors via business course students and positioning it as a study about “workplace stressors, employee downtime, and work-related wellbeing”, as well as via a social media page dedicated to cannabis use. For the latter, participants’ supervisors were contacted with no reference to cannabis usage. 

Participants were asked to self-report their levels of cannabis usage, as well as the times at which cannabis was used. Supervisors, meanwhile, were asked to rate their employee’s task performance on a seven-point scale, covering three key areas:

• Task performance
• Organisational citizenship behaviours (OCBs)
• Counterproductive work behaviours (CWBs)

The study’s creators were looking to test three hypotheses:

• Hypothesis 1: Cannabis use (a) prior to starting the work day and (b) while on the job negatively correlates with task performance; (c) cannabis use after work positively correlates with task performance.
• Hypothesis 2: Cannabis use (a) prior to starting the work day and (b) while on the job negatively correlates with OCBs; (c) cannabis use after work positively correlates with OCBs.
• Hypothesis 3: Cannabis use (a) prior to starting the work day and (b) while on the job positively correlates with CWBs.

The results revealed correlation between before and during work cannabis use with all three hypotheses, but no positive correlation between after-work usage and either task performance or organisational citizenship behaviours. It also showed that after-work cannabis use did not impair participants’ work the following day. 

What does this mean for workplace drug testing? 

The results of this study suggest that the use of cannabis both before and during the working day can have a detrimental impact on an individual’s performance, and in a number of ways. 

However, it also states that “after-work cannabis use did not predict a single form of performance as rated by one’s direct supervisor”, which may lead some to believe that individuals can use cannabis after work without it impairing their workplace performance in any way. 

The study creators themselves advise some degree of caution. Studies such as this, which was published in Basic and Applied Psychology, reveal that individuals tend to under-report behaviours - like drug use - that can be seen as socially undesirable. 

In addition, while the study does show some correlations, it does not show cause and effect. While it may be that before and during work usage contributes to negative behaviours, it may also be that work-related stress has led to increased cannabis use. 

In many companies, across many industries, workplace drug testing programmes will include post-incident testing as well as random testing, and, in some cases, pre-employment testing too. Post-incident and random testing can be conducted using oral fluid, blood or urine testing - with oral fluid being our recommendation. 

With a detection window of one to two days, oral fluid testing is an accurate, reliable way of establishing whether an individual is under the influence at the time of testing. While urine testing is also accurate, it has a broader testing window of up to five days. This could potentially mean, for example, that an individual may have smoked cannabis on a Friday night and could still test positive on Monday morning, with the test picking up residue traces. Urine testing also requires a certain level of privacy to conduct, meaning that it can be easier for individuals to tamper with samples than when an oral fluid sample is taken instead. 

For continual monitoring or pre-employment testing, hair testing is our preferred method. This method of testing for cannabis use will allow employers to establish usage trends over several months. 

For companies with a zero tolerance drug policy, any individual with a positive hair test will be either disciplined or entered into a rehabilitation program, depending on the industry and the levels of cannabis use detected in the results - regardless of their performance at work. 

Cannabis use in the UK is on the rise, and use of the drug is regularly linked with increased anxiety and depression, and the risk of developing psychotic illnesses down the line. Studies also show that use of synthetic cannabinoids - which can have severe, unpredictable or even life-threatening effects - can be linked with use of other substances such as cannabis. 

Should dependency increase, those who previously only consumed the drug after work could increasingly find that they need to use it before and/or during work to feel “normal”. For this reason, we maintain that, while the study in question may reveal no negative link between post-work usage and workplace performance, it cannot predict the likelihood of increased dependence and future work-related problems. 

Hair testing allows workplaces to establish an individual’s level of cannabis use, and can monitor this over time. Any increases can be discussed straight away and the relevant support given to avoid further problems in the future. 

To find out more about how hair drug testing can benefit your own workplace, get in touch. 

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