Insomnia in adolescents and youth is a long-standing public health concern due to its high prevalence and association with various physical and mental health problems. Insomnia and psychiatric disorders are highly comorbid and intercorrelated in adolescents. Among all mental disorders, anxiety has been shown to be have high comorbidity with insomnia, affecting approximately 30% of individuals. CBT for insomnia (CBT-I) has been shown to be effective in improving sleep complaints and short-term improvement in mood while previous systematic reviews of interventional studies have demonstrated the effectiveness of acceptance and commitment therapy (ACT) interventions in treating insomnia, both as a primary condition and with other physical and/or mental health comorbidities. This study aims to compare the effect of CBT-I and CBT-I combined ACT in improving anxiety symptoms in youth.

Insomnia and psychiatric disorders are highly comorbid and intercorrelated in adolescents. Among all mental disorders, anxiety has been shown to be have high comorbidity with insomnia, affecting approximately 30% of individuals. Moreover, approximately three-quarters of anxious youth also report sleep-related problems. Literature reviews have investigated the relationship and the shared underlying mechanisms between sleep and anxiety. Anxiety sensitivity and pre-sleep arousal have been found to play a critical role in difficulty initiating sleep, which is the most common insomnia symptoms in adolescent population, partially due their natural delay of circadian rhythm. The findings suggest shared neurological and cognitive features that may account for dysregulation of both sleep and affect. Management targeting both sleep and anxiety is recommended due to potentially higher treatment efficacy and cost-effectiveness.

Accumulating evidence supports the effectiveness of cognitive-behavioural therapy for insomnia (CBT-I) and acceptance and commitment therapy (ACT) for addressing sleep and mood problems in adolescents. However, Only a few studies have directly compared the effectiveness of CBT-I and ACT. Past studies have shown that both CBT-I and ACT were effective in treating insomnia in adults.

This current study aims to compare the effect of CBT-I and CBT-I combined ACT in improving anxiety symptoms in youth. The primary hypothesis is that subjects in CBT-I combined ACT will have fewer anxiety symptoms as compared to CBT-I at post-intervention and 3-month follow-up.

Inclusion Criteria:

Youth who meet the following criteria would be eligible for taking part in this trial:

i. Chinese youth aged 15-24 years old, ii. Presence of insomnia problems as defined by insomnia severity index (ISI) using cut-off of 9, which has been locally validated cut off for detecting clinical insomnia), iii. Presence of anxiety features as defined by General Anxiety Disorder-7 (GAD-7) using cut-off of 10 for detecting clinical anxiety, iv. Ability to listen, speak, and read Chinese and Cantonese, and v. Written informed consent of participation into the study is given by youth and his/her parent's if under 18 years old; In addition, individual assent will also be obtained for subjects under age 18 years old vi. Possession of smartphone

Exclusion Criteria:

A youth would be excluded from the study if meeting one or more of the following criteria:

i. A clinical diagnosis of psychosis, schizophrenia, bipolar disorders, or intellectual disability ii. Having a diagnosed sleep disorder (e.g. delayed sleep phase and narcolepsy) that may potentially contribute to the disruption of sleep quantity and quality as determined by validated Diagnostic Interview for Sleep Patterns and Disorders (DISP) iii. Having a clinically significant suicidality (presence of suicidal ideation with a plan or an attempt) as assessed by The Structured Clinical Interview (SCID) iv. Currently receiving psychological treatment and/or pharmacological treatment for insomnia or anxiety disorder.