Young people who prefer to stay up late are more impulsive than their peers who go to bed earlier, which makes them more likely to drink alcohol and smoke, according to a study in the journal Chronobiology International, reports the University of Surrey. Simple actions to improve sleep might help to reduce substance use and anxiety in vulnerable young adults.
In the first study of its kind, researchers from the University of Surrey and Brunel University London investigated how being an evening type (someone who prefers to stay up late and functions better in the evening) links to impulsivity, anxiety and substance use.
Young people often prefer to stay up late, and those who do are known to be at higher risk of mental health issues and problematic substance use, writes Natasha Meredith for the University of Study in material published on 14 December 2020.
To better understand why this is, researchers recruited 191 participants aged between 18-25 years old. Participants were surveyed on their sleeping preference (morning or evening types), their sleep quality, levels of anxiety and impulsivity, and asked about how many cigarettes they smoked and how much alcohol, coffee, and other caffeinated drinks they consumed.
A lab-based computer test was also used to test impulsivity levels. Participants were required to indicate how long they were willing to wait before receiving a hypothetical cash reward.
Researchers found that evening types were more impulsive, preferring small immediate rewards over delayed larger ones. These young adult evening types were also more anxious and reported higher alcohol, caffeine and cigarette use compared to their peers who preferred going to bed earlier.
Lower sleep quality did not explain these effects; to see what could, researchers used a statistical method known as mediation analysis, which found that higher levels of impulsivity were the link between being an evening type and greater alcohol, caffeine and cigarette use.
Researchers believe that by understanding what causes young people to smoke and drink more, we can educate them more effectively about risk factors and design strategies to combat problematic substance use.
Dr Simon Evans, Lecturer in Neuroscience at the University of Surrey, said: “Young people who stay up late and claim they function best in the evening are known to have higher alcohol intake, smoke more cigarettes and are at greater risk of mental health issues. What we have found is that their higher levels of substance use are due to their increased impulsivity levels.
“The consequences of high levels of substance use can be detrimental to long term physical and mental health, and these findings suggest ways we could reduce risky substance use behaviours in young people.”
Dr Ray Norbury, Senior lecturer in Psychology at Brunel University London, said: “We found that the tendency to be a night owl was associated with higher levels of anxiety, impulsivity and alcohol and cigarette use.
“What we don’t know is if night owls are more likely to engage with these harmful behaviours because they are already out late and so may just have more exposure to opportunities to drink and smoke or whether the addictive behaviours (the stimulant effects of smoking for instance) drive them to be up late.
“Clearly, this study has implications for both the mental and physical health of our student populations. It may be that simple interventions to improve sleep hygiene could reduce substance use and anxiety in these young and potentially vulnerable adults.”
Associations between diurnal preference, impulsivity and substance use in a young-adult student sample
Chronobiology International. Published in November 2020.
Simon L Evans and Ray Norbury
A diurnal preference for eveningness is common in young adulthood and previous research has associated eveningness with anxiety symptoms as well as increased smoking and alcohol use behaviors.
There is some evidence that impulsivity might be an important explanatory variable in these associations, but this has not been comprehensively researched. Here we used both subjective and objective measures of impulsivity to characterise impulsive tendencies in young adults and investigated whether trait impulsivity or trait anxiety could mediate the link between eveningness and substance use.
A total of 191 university students (169 females), age range 18–25 y, completed the study. Diurnal preference, sleep quality, anxiety, impulsivity, and substance use were assessed by questionnaire. Impulsivity was also measured using a delay discounting task.
Eveningness correlated with trait anxiety and trait impulsivity, and these associations were still significant after controlling for sleep quality. On the delayed discounting task, eveningness correlated with a tendency to prefer smaller immediate rewards over delayed, larger ones.
Evening types also reported higher levels of alcohol and cigarette use even after controlling for sleep quality. These associations were found to be completely mediated by self-reported impulsivity; anxiety did not contribute. The current results could help inform interventions aiming to reduce substance use in young adult populations.
University of Surrey material – Young people who go to bed later drink and smoke more due to their impulsivity
Chronobiology International article – Associations between diurnal preference, impulsivity and substance use in a young-adult student sample