Background and objective: This study aims to determine the effects of forest activities, such as forest meditation and forest experience, on young children's sleep and problematic behaviors and to compare the changes that occur according to the type of forest activity.Methods: Fifty-nine five-year-old children from early childhood education institutions in Cheongju City, Korea, participated. The experiment took place over five weeks between May 3 and 31, 2022. Activities were conducted twice a week for a total of eight sessions. The forest meditation and forest experience groups carried out activities in the forest. The control group carried out thematic activities according to the Nuri curriculum followed by early childhood education institutions. The Korean version of the Children's Sleep Habits Questionnaire was used to assess the participants' sleep duration and sleep habits, and the Korean Child Behavior Checklist for Ages 1.5-5 was used to assess problematic behaviors.Results: We found a statistically significant increase in the average sleep duration of the children in the meditation group, as well as a statistically significant decrease in their total sleep habits score and the scores of the bedtime resistance, sleep onset delay, and sleep anxiety subdomains of sleep habits. A statistically significant decrease was observed in the forest experience group's scores for total problematic behaviors and internalizing problems. We also found a statistically significant positive correlation between sleep habits and problematic behaviors.Conclusion: These findings demonstrate that static activities, such as forest meditation activities, increase sleep duration and improve sleep habits, while dynamic activities, such as forest experience activities, improve problematic behaviors and internalizing problems. Providing specific programs that appropriately utilize static and dynamic forest activities can help improve sleep and problematic behaviors in young children.