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Background: Research on cannabis has focused on lifetime use or regular/heavy use (i.e., daily or almost daily). Regular, albeit not necessarily daily, cannabis use has received less scientific attention. Objectives: This study aims to identify demographic and personality factors associated with recurrent cannabis use (i.e., cannabis usage 5 to 50 times in the last six months) and to investigate the relationship between cannabis use and use of other substances. Methods: Public and private university students ( N = 11,236) in Bergen, Norway, participated in an online survey during autumn 2015. Binary logistic regression was run to identify individual characteristics related to recurrent cannabis use. Chi-square tests were conducted to investigate differences in substance use (alcohol, nicotine, and illicit drugs) between recurrent cannabis users and cannabis abstainers/low-frequency users. Results: A total of 4.0% of the students reported recurrent cannabis use. Students born in North America, non-Christians (compared to non-religious students), and men were more likely to be recurrent users. Recurrent cannabis users scored higher on extroversion and intellect/imagination compared to abstainers/low-frequency users. Male and female recurrent cannabis users had somewhat different characteristics (e.g., agreeableness scores were negatively associated with recurrent use among females but not among males). Recurrent cannabis use was overall strongly associated with polysubstance use. Conclusions: The prevalence of recurrent cannabis use among Norwegian students is low. Recurrent cannabis use seems more prevalent among individuals marked by extroversion and intellect/imagination, which supports the notion of cannabis use as a social activity for individuals identifying themselves as outgoing and unconventional. Cannabis use among students seems strongly associated with use of other substances, suggesting that cannabis should not be considered a replacement drug.

Aims: This study investigates demographic, personality, and psychological health correlates of different drinking patterns. Design: Students at the four largest institutions of higher education in Bergen municipality were invited via email to complete an internet-based questionnaire. The final sample size was 11,236 (39.4%), mean age 24.9 years ( SD = 6.5), and 63.3% were women. The survey included the Alcohol Use Disorder Identification Test (AUDIT) and questions about demographics, personality traits, and symptoms of depression and anxiety. Binary logistic regressions were used to identify correlates of different drinking patterns. Results: A total of 53.0% of the students had an AUDIT score of or above 8 (i.e., hazardous drinking). Being native Norwegian, male, single, without children, non-religious, extroverted, unconscientious, and less open to experience were associated with higher AUDIT scores, drinking frequently, and binge drinking. Having parents with high alcohol or drug use increased the odds of engaging in binge drinking, but this factor was not associated with frequent drinking. Students scoring higher on neuroticism and openness were less likely to report problematic alcohol usage. Conclusions: A majority of the students reported alcohol habits that are associated with harm if they persist. This emphasises the need to examine the long-term consequences of students’ alcohol use.

Delayed sleep phase disorder (DSPD) is a circadian rhythm sleep disorder. Patients with DSPD have problems initiating sleep if they go to bed at a conventional time, and they often have problems waking at desired times. If they rise early in the morning, they usually experience severe sleepiness during morning hours. In the present study, we investigated the short- and long-term effects on measures of subjective and objective sleepiness and cognitive function of bright light and melatonin treatment alongside gradually advanced rise times in adolescents and young adults. Four treatment conditions were used in the short-term intervention (2 weeks): dim light (placebo) + placebo capsule, bright light + placebo capsule, dim light (placebo) + melatonin capsule, and bright light + melatonin capsule. This was followed by a long-term intervention (3 months) including 2 conditions: no treatment and combined bright light + melatonin treatment. Effects of treatment on sleepiness and fatigue were the primary outcome measures, and effects on cognitive function were secondary outcome measures. On a gradual advancement of the rise time schedule, all treatment conditions (bright light, melatonin, combination, and placebo) were almost equally effective in improving subjective daytime sleepiness, fatigue, and cognitive function in the 2-week study. The 2-week intervention showed no effect on objective sleepiness. Long-term treatment increased some of the positive effects seen after 2 weeks. The combined bright light and melatonin treatment improved subjective daytime sleepiness, fatigue, and cognitive function in the 3-month study. The no-treatment group returned to baseline values on most variables. In conclusion, a gradual advancement of rise times seems to produce positive effects on subjective sleepiness, fatigue, and cognitive performance during short-term treatment of patients with DSPD. However, the benefits from gradually advanced rise times seem to wear off, suggesting that the continuation of bright light and melatonin treatment is beneficial to maintain positive effects over time.