Recent scientific studies have shed light on the connections between our body’s internal clock, substance use, and mental health. One study, published in Frontiers in Neuroscience in 2022, suggests that our natural sleep-wake cycles, known as chronotypes, intertwine with the use of substances, affecting our mental wellbeing. Another study, published in European Addiction Research in 2023, indicates that people who struggle with cocaine addiction tend to experience greater social jetlag – a misalignment between one’s biological and social schedules.
The motivation behind these studies stemmed from a growing concern about the increased usage of substances and a parallel rise in mental health issues, particularly during stressful periods like the COVID-19 pandemic. The researchers were curious about how the use of psychoactive substances such as cocaine could influence our chronotype—whether we are morning larks or night owls—and how this interplay impacts our mental health.
“Circadian rhythmicity is the base of all of our daily behaviors, and disruption of normal circadian functioning may lead to a mismatch between biological and social time, known as social jetlag,” explained study authors Jeevan Fernando, a junior doctor at Oxford University Hospitals, and Karen D. Ersche, a professor of addiction neuroscience at the University of Cambridge.
“Disruption of circadian rhythm is associated with many psychiatric disorders, especially substance use disorders as drugs of abuse interfere with our sleep/wake cycle. However, very little is known about changes in circadian rhythmicity and social jetlag in patients with cocaine use disorder.”
The Frontiers in Neuroscience study involved 209 participants who were recruited through online platforms and physical advertisements in Cambridge, United Kingdom. The participants completed a series of questionnaires assessing their chronotype, substance use (alcohol, cannabis, and tobacco), and mental health status. The Munich Chronotype Questionnaire, Alcohol Use Disorders Identification Test, Revised Cannabis Use Disorders Identification Test, Fagerström Test for Nicotine Dependence, and the Depression, Anxiety and Stress Scale were among the tools used to gather data.
Findings from this study indicated a significant link between late chronotypes (night owls) and poorer mental health, particularly in terms of increased anxiety. This relationship was further found to be influenced by the combined use of alcohol, tobacco, and cannabis. The increased consumption of these substances among late chronotypes seemed to mediate their mental health challenges. In other words, the increased use of these substances among late chronotypes explained the association between their chronotype and heightened anxiety levels.
Following this, the European Addiction Research study in 2023 delved deeper, focusing specifically on cocaine use disorder. This research involved 90 men from the local community, including 48 with moderate-to-severe cocaine use disorder and 42 healthy controls. Participants underwent psychiatric screening, provided urine samples to test for drug use, and completed the Munich Chronotype Questionnaire to assess their sleep-wake patterns. The study aimed to understand the chronotype distribution among cocaine users and its potential implications for their health.
“Given that cocaine use is a growing public health problem in the United Kingdom, for which effective treatments are lacking, we sought to investigate self-report chronotype in a community sample of chronic cocaine users,” Fernando and Ersche said. “Insight into the changes in chronotype may provide new avenues to improve general health and wellbeing for a cocaine use disorder for which successful treatment has yet to be established.”
One of the key findings was that late chronotypes (or “night owls”) were more prevalent in the cocaine group compared to controls. Interestingly, a significant number of cocaine users reported a shift from an early to a late chronotype from childhood to adulthood, a pattern not evident among the control group.
“Cocaine users with late chronotype tended to have started using cocaine at an earlier age,” Fernando and Ersche told PsyPost. “These findings, combined with the existing literature and our previous work may suggest that late chronotype presents a risk factor for increased drug use. This is also in keeping with other studies showing that being a night owl is associated with poorer health and wellbeing more generally. Our study further highlights the importance of the impact this may have on our social life as it leads to social jetlag – an aspect that is often overlooked.”
Another significant observation was the presence of greater social jetlag in cocaine users, indicated by a mismatch between their biological and social times. This mismatch was not influenced by drug and alcohol use but was somewhat related to employment status, as most cocaine users were unemployed. This finding suggests that employment might provide a temporal anchor that could improve the circadian rhythms of those struggling with cocaine use.
“Further research is warranted to evaluate whether regular employment, which may give chronic cocaine users a structure in their daily lives could help counteract the negative effects of social jetlag,” the researchers said.
However, contrary to expectations, the severity of cocaine use and chronotype were not directly related. Mental and physical health statuses were consistent across different chronotypes, suggesting that changes in these health variables were more associated with the diagnostic group (cocaine users vs. control) than with chronotype.
“It was quite interesting that our findings did not show any relationship between chronotype, or social jetlag, with addiction severity,” Fernando and Ersche explained. “This supports the notion that late chronotype may be a risk factor for an earlier onset of drug use, which in turn increases the risk of developing drug addiction, but it may not influence the level of addiction severity.”
The new study offers valuable insights but also has limitations. The cross-sectional nature of the research means that while relationships between factors can be identified, cause and effect cannot be established. Future research might include longitudinal studies that track individuals over time to better understand the direction of these relationships. Additionally, exploring the quality of sleep and other lifestyle factors could provide a more comprehensive picture of how our internal clocks, substance use, and mental health are intertwined.
“Although our study had many advantages, including face-to-face assessment of participants using sophisticated research tools, it had a cross-sectional design, i.e. we compared groups at a single time point,” Fernando and Ersche said. “We collected information about childhood or adolescence chronotype retrospectively from our participants. This approach revealed that a larger percentage of patients with cocaine use disorder reported a change from early chronotype during childhood/adolescence to late chronotype during adulthood compared with their non-drug using peers. It would be good if this finding could be verified in a longitudinal study.”
The study, “Drug Use in Night Owls May Increase the Risk for Mental Health Problems“, was authored by Jeevan Fernando, Jan Stochl, and Karen D. Ersche.
The study, “Mismatch of Biological and Social Time in Cocaine-Addicted Men“, was authored by Jeevan Fernando and Karen D. Ersche.
