Study background: Mild to severe sleep problems are reported in 3% to 56% of young children. Behaviourbased treatments are highly effective in improving children´s sleep. The purpose of this work was to examine the efficacy of an Internet-based intervention for young children´s sleep disturbances (Mini-KiSS Online) and to assess the effect of telephone support for parents.

Methods: Two intervention conditions (written information with or without additional weekly telephone support) were compared to a waiting-list control condition. N=199 parents with their children (aged 6-63 months) were randomly assigned to one of the study conditions. The treatment consisted of six written information modules based on a cognitive-behavioural approach. One of the treatment groups had additional weekly telephone support. Data of sleep diary, parental behaviour, CBCL 1.5-5 (pre, post, 3-month follow-up) and treatment evaluation were collected.

Results: Acceptance of Mini-KiSS Online was high. Children in both treatment conditions showed significant increase in sleep efficacy and reductions in sleep onset latency, duration of night waking, or subjective global ratings while there was no or less change in the control condition. Parents of both treatment conditions reduced their parental presence and physical contact to the child. A benefit of personal assistance was found for treatment evaluation and dropout rates.

Conclusion: Mini-KiSS Online is an effective and highly accepted internet-based intervention to reduce sleep problems in young children. Personal telephone assistance counted for higher satisfaction and lower dropouts but not for further improvement of the sleep behaviour of the child.