A new seven-day study that followed sleep patterns of adolescents found that negative mood during the day was related to greater sleep/wake problems and shorter sleep duration. Happiness was related to lower sleep/wake problems. But actigraphy measures of sleep showed somewhat different results. The study was published in Child Development.
Sleep-related problem trouble a large proportion of adolescents worldwide. Short sleep duration is related to daytime sleepiness in adolescents. Both short sleep duration and poor sleep quality are often indicators of other psychological problems. A growing body of research indicates that mood has an important role in sleep in adolescents. Sleep quality can be disrupted by mood, but mood can also be affected by sleep related issues. The association between sleep and mood seems to go in both directions.
Adolescence is a particularly important developmental period for the study of sleep. Hormonal changes happening in adolescence have been shown to affect the drive for sleep. These are thought to lead adolescents to want to go to sleep later, rather than decrease the amount of sleep they need. Additionally, brain development in adolescence may occur primarily during sleep and it has been shown to support mood regulation.
To study the relationship between sleep and mood, Chrystyna D. Kouros and her colleagues analyzed data from the fourth wave of the Auburn University Sleep Study, a longitudinal study focusing on sleep and health. The study included 323 adolescents and their families. The average age of participants was 17 years and 52% were female. The study followed their sleep behavior for seven days.
Sleep was assessed objectively, by having participants wear an actigraph (a wrist-worn device that records movements of the limb) and subjectively, by having adolescents keep a daily sleep diary in which they answered a number of questions about their sleep that day. “Each night that adolescents wore the actigraph, they also completed a daily sleep survey, in which they rated how they felt that day on a 5-point Likert scale,” the researchers explained.
Assessments of the mood of participants on each particular day were produced based on their answers. Actigraphy recordings were used to produce estimations of sleep quantity, quality, and efficiency. Sleep efficiency is the portion of time a person spends sleeping out of the total time he/she spends in bed (trying to sleep).
Results showed that greater happiness was associated with less sleep/wake problems, but with a somewhat lower sleep efficiency on the night after the day on which happiness was assessed. More self-reported sleep/wake problems were associated with more pronounced negative mood on the same day. More pronounced negative mood was associated with more time spent sleeping and more efficient sleep, both as recorded by the actigraph.
When comparing sleep characteristics with happiness and negative mood on the next day, results showed shorter sleep duration and more problems in sleeping and waking up were associated with more negative mood the next day. However, these results were obtained only for subjective sleep measures, not for objective ones.
“Better mood (higher happiness and lower negative mood) predicted better quality sleep and worse mood predicted worse quality sleep,” the study authors wrote and concluded that “in order to fall asleep, persons must feel safe and enter a state of relaxation. In order to maintain vigilance to threats in the environment and consciously process information, persons must be awake. It is possible that adolescents who are experiencing negative mood or low positive mood during the day are ruminating at night, which is a state of cognitive pre-sleep arousal in which adolescents are maintaining a state of conscious processing of thoughts.”
While the study makes an important contribution to the knowledge about psychological mechanisms of sleep, the authors note that some of the actigraph measures ran counter to their expectations and to subjective measures. Also, all the associations were examined in adolescents of roughly the same age and results on people of different age might not be the same.
The paper, “Bidirectional associations between nightly sleep and daily happiness and negative mood in adolescents”, was authored by Chrystyna D. Kouros, Peggy S. Keller, Olivia Martín-Piñón, and Mona El-Sheikh.
