Wasn't It Supposed To Be Relaxing? Study Shows That Frequent Cannabis Use Can Alter The Brain's Stress System

Many people use cannabis to relieve stress, but a new study suggests the long-term effect may be quite different. Researchers found that frequent users wake up with higher levels of cortisol, the main stress hormone, revealing that the brain and body can remain in a state of alertness even after hours without consuming the substance.

Cannabis is one of the most widely used psychoactive substances in the world and, for many people, is seen as a way to relieve anxiety and stress. In fact, soon after use, some people report a feeling of relaxation. But what happens to the brain and body when this consumption becomes frequent?

A new study investigated precisely this question and found evidence that habitual cannabis users wake up with higher levels of cortisol, known as the main stress hormone.

Cortisol is produced by the adrenal glands and is part of the body's main stress response system. In challenging situations, it helps the body increase energy, maintain attention, and prepare the brain to react quickly. Normally, its levels increase right after we wake up and gradually decrease throughout the day.

However, when this system remains activated for long periods, it can affect brain function, influencing regions such as the hippocampus, important for memory, the prefrontal cortex, responsible for self-control and decision-making, and the amygdala, which participates in the processing of emotions and fear.

To understand how cannabis can interfere with this mechanism, researchers compared two groups of adults: people who frequently used cannabis and healthy individuals who did not use the substance.

For two consecutive days, all participants answered questionnaires about their stress levels and collected saliva samples at three times of the day: immediately upon waking, thirty minutes later, and during the night. Saliva allows for a simple and comfortable measurement of cortisol levels, making it one of the most widely used methods for studying the biological response to stress.

Scientists expected to find differences in the natural increase in cortisol after waking, a phenomenon considered an important indicator of the stress response system's activity. Interestingly, this increase was similar in both groups.

The big difference appeared right when people woke up. Frequent cannabis users already had significantly higher cortisol levels even before the physiological increase that occurs in the morning.

Furthermore, the greater the difficulties and problems related to cannabis use reported by the participants, the higher their cortisol levels were upon waking. This suggests that frequent use of the drug may be associated with a persistent alteration in the functioning of the biological system that regulates stress.

Although many people use cannabis precisely to try to relax, these results indicate that, in the long term, the body can remain in a state of greater physiological activation.

The researchers emphasize that the study does not demonstrate that cannabis is the direct cause of the increase in cortisol, but it does reveal an important association between frequent use of the substance and changes in the biology of stress.

These findings help to understand why some people may develop an increasingly intense pattern of use and reinforce the need for further studies to investigate how these changes in the brain and body can influence mental health and the risk of addiction over the years.

READ MORE:

Subjective Stress and Diurnal Salivary Cortisol in Adults with Frequent Cannabis Use

Julia Donner, Alexia N. Obrochta, and Anita Cservenka

Cannabis. 9 June 2026DOI: 10.26828/cannabis/2026/000390

Abstract: 

The hypothalamic pituitary adrenal (HPA) axis, the major neuroendocrine system that responds to stress, may be dysregulated by substance use. The rise of cortisol in the morning, known as the cortisol awakening  response  (CAR),  is  believed  to  be  a  reliable marker  for  individual  differences  in  HPA  axis activity.  The  purpose  of  this  study  was  to  investigate  differences  in  the  CAR  between  individuals  with frequent  cannabis  use  (CU)  and  healthy  controls  (HC)  and  determine  whether  cannabis  use  status moderates the relationship between subjective stress and cortisol levels. 39 CU and 43 HC reported subjective  stress  levels  and  collected  daily  saliva  samples  at  awakening,  30  minutes  later,  and  in  the evening, on two consecutive weekdays. We examined group differences in the CAR (30 min post awakening awakening cortisol), and the association between stress and cortisol levels at each collection time with group entered as a moderator in regression analyses. There were no significant group differences in the CAR (p = .23). At awakening, subjective stress was positively related to cortisol levels (p = .001) and CU had higher cortisol than HC (p= .047), which was significantly related to consequences of cannabis use (p= .007). While the rise of the CAR did not differ between groups, individuals with frequent cannabis use exhibited significantly higher basal cortisol levels at awakening. This elevation was positively correlated  with  cannabis related  consequences,  suggesting  that 

awakening  cortisol  may  serve  as  a neurobiological marker of problematic cannabis use and warrants further investigation.