Self-control fluctuates from day to day and is linked to subjective well-being within and between persons.

The psychological trait of self-control has been linked to interindividual differences in subjective well-being: Individuals with higher self-control report less negative affect, more positive affect, and higher life satisfaction. However, less is known about how much self-control fluctuates from day to day and how these fluctuations are related to subjective well-being. This intensive longitudinal study describes day-to-day fluctuations in self-control and investigates whether and how they are related to subjective well-being. A sample of 64 undergraduate students at the entry phase of university (M = 22.55 years, SD = 6.51, range = 18-53, 97% female) provided 1459 reports of their self-control and subjective well-being, collected every evening across three 9-day measurement bursts over 6 months. Participants' self-control fluctuated substantially from day to day with less than 40% of the variability in daily self-control being attributable to interindividual differences in self-control. On days with higher self-control, participants reported less negative affect, more serenity, and higher life satisfaction. We found no relationship between self-control and vigor. The findings suggest that researchers need to go beyond current assessment practices and theories treating self-control as a stable trait to help develop tailored well-being interventions for everyday life.

The Association of Self-Reported ADHD Symptoms and Sleep in Daily Life of a General Population Sample of School Children: An Inter- and Intraindividual Perspective.

Sleep and Attention-Deficit/Hyperactivity Disorder (ADHD) have repeatedly been found to be associated with each other. However, the ecological validity of daily life studies to examine the effect of sleep on ADHD symptoms is rarely made use of. In an ambulatory assessment study with measurement burst design, consisting of three bursts (each 6 months apart) of 18 days each, 70 German schoolchildren aged 10-12 years reported on their sleep quality each morning and on their subjective ADHD symptom levels as well as their sleepiness three times a day. It was hypothesized that nightly sleep quality is negatively associated with ADHD symptoms on the inter- as well as the intraindividual level. Thus, we expected children who sleep better to report higher attention and self-regulation. Additionally, sleepiness during the day was hypothesized to be positively associated with ADHD symptoms on both levels, meaning that when children are sleepier, they experience more ADHD symptoms. No association of sleep quality and ADHD symptoms between or within participants was found in multilevel analyses; also, no connection was found between ADHD symptoms and daytime sleepiness on the interindividual level. Unexpectedly, a negative association was found on the intraindividual level for ADHD symptoms and daytime sleepiness, indicating that in moments when children are sleepier during the day, they experience less ADHD symptoms. Explorative analyses showed differential links of nightly sleep quality and daytime sleepiness, with the core symptoms of inattention and hyperactivity/impulsivity, respectively. Therefore, future analyses should take the factor structure of ADHD symptoms into account.