Sleep, stress, and mental health in adolescents with chronic insomnia: An intensive longitudinal study with experimental design

• Applicants: Professor Dr. Pertti Sakari Lemola; Professor Dr. Arnold Lohaus
• Subject Area: Personality Psychology, Clinical and Medical Psychology, Methodology ; Developmental and Educational Psychology
• Term: since 2018
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 396253397

Background: Insomnia symptoms are common in adolescence and they often precede the onset of internalizing disorders, particularly depression. "Sleep restriction intervention" has been shown to be a highly effective treatment to improve insomnia and there is evidence suggesting that it might also lead to improvement in comorbid internalizing symptoms. However, research focusing on the mechanisms evoked by sleep restriction and the mediators by which sleep restriction improves insomnia symptoms and internalizing symptoms is limited. In particular, studies examining the role of worrying and rumination during the night as well as sleep duration for internalizing symptoms on the following day are missing. Moreover, the role of the hypothalamic-pituitary-adrenocortical (HPA) axis activity for insomnia symptoms and how HPA axis activity is affected by sleep restriction is not yet well-understood. Aims: As a first aim, we examine through which mechanisms experimental sleep restriction evokes improvement in insomnia symptoms. Relatedly, we examine whether and through which mechanisms the improvement in insomnia symptoms leads to improvement of internalizing symptoms. As a second aim, based on an experience sampling approach, we examine whether insomnia symptoms are associated with the subjective experience of stress and internalizing symptoms on the following day and, in particular, which role worrying and rumination during the night as well as sleep duration play for this association. As a third aim, to further the understanding of the etiology of insomnia, we also examine the association of the HPA axis activity (i.e., cortisol secretion in the morning and in the evening) with insomnia symptoms of the preceding and subsequent night and how cortisol secretion is affected by experimental sleep restriction. Method: A 4-week intensive longitudinal study (involving smartphone-based experience sampling, daily diaries, weekly surveys, actigraphy, and saliva cortisol sampling) with experimental sleep restriction is conducted with adolescents aged 16-19 years with chronic insomnia. Participants are randomly assigned to an experimental sleep restriction group and a comparison group that only receives information about sleep hygiene but no experimental sleep restriction. The experimental sleep restriction protocol aims to mimic the procedure used in sleep restriction treatment; after one week of baseline assessment, the experimental sleep restriction begins in week 2 when the "time in bed" (TIB) in the experimental group is restricted to the duration of the total sleep time as recorded during the baseline week for each individual. Across weeks 3 and 4, TIB in the experimental group is gradually extended again. We will analyze indirect causal effects using mediation analyses and conduct dynamic structural equation modeling for data with multilevel structure.

• DFG Programme: Research Grants