In France, over half of students suffer from sleep complaints. These are particularly concerning as they can affect the success of their studies, and their physical and mental health. A real public health issue, the evaluation of these health risks is one of the research subjects of a team of scientists from Inserm, Université de Bordeaux and Bordeaux University Hospital. In a new study published in Psychiatry Research , they focused on cannabis use by students - with the knowledge that its consumption among 18-25-year-olds in France is particularly high - and tried to measure its effects on sleep. What they found was that cannabis use increased the risk of sleep disturbances, with the frequency of insomnia doubling among those who smoke it daily. This study was conducted based on the analysis of the data of 14,787 student volunteers, who are members of the i-Share cohort.
Poor sleep quality has been shown to affect 55% of students and insomnia 19%. These sleep alterations are all the more concerning because of their detrimental effects on mental health, physical health, and cognitive capacities - with a subsequent negative impact on the students’ academic success.
Some studies have already investigated the causes of these disturbances, particularly in relation to cannabis use, the level of which is particularly high among young people in France: 13.9% of 18-25-year-olds report using it monthly and 4% daily  .
In this new article, researchers from Inserm, Université de Bordeaux and Bordeaux University Hospital at the Bordeaux Population Health research center have for the first time conducted an in-depth analysis of the association between cannabis use and sleep disturbances in a sample of 14,787 university students. These participants all come from the i-Share cohort that studies the general health of students, which is led by the last author of this study, Christophe Tzourio.
The students answered an online self-questionnaire on the frequency of their cannabis use over the past year (daily, weekly, monthly or rarely/never), as well as the quality of their sleep in the last three months  , with a question specifically about insomnia. Other questions concerned their sociodemographic characteristics, lifestyle (e.g. alcohol or tobacco consumption) and mental health, in order to refine the analysis and avoid any bias or confounding factors.
The results of this study confirm the existence of an association between cannabis use and sleep disturbances, particularly insomnia, among students. The likelihood of suffering from insomnia was found to be 45% higher in cannabis users compared to non-users, reaching a 2-fold higher likelihood compared to never/rarely users.
"The originality of this study lies in the fact that we had access to a particularly large sample of students who provided accurate data on their cannabis use and sleep quality. The richness of the data collected through the questionnaires provides new evidence of the association between insomnia and cannabis use,” explains Julien Coelho, first author of the study.
"Although causality cannot be confirmed with certainty, these findings suggest the importance of stepping up public health messages for the purposes of prevention among students, as well as raise the awareness of health professionals on the dangers of high levels of cannabis use on the health of young people,” concludes Tzourio.
 Source: Santé publique France Health Barometers, with data utilization by the French Monitoring Centre for Drugs and Drug Addiction (OFDT)
 The questions focused on four items: insomnia, sleepiness, poor sleep quality, and sleep deprivation.