{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T10:07:49Z","timestamp":1779185269595,"version":"3.51.4"},"reference-count":26,"publisher":"MDPI AG","issue":"10","license":[{"start":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T00:00:00Z","timestamp":1779148800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001691","name":"JSPS KAKENHI","doi-asserted-by":"publisher","award":["25K14911"],"award-info":[{"award-number":["25K14911"]}],"id":[{"id":"10.13039\/501100001691","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Healthcare"],"abstract":"<jats:p>Background: Insomnia symptoms associated with late chronotypes are prevalent among young adults, and frequently lead to sleep deprivation, morning-awakening difficulties, and excessive daytime sleepiness. These conditions are associated with psychological distress, impaired academic functioning, and reduced self-esteem. Although chronobiological behavioral interventions are effective, their accessibility remains limited. To bridge this gap, we developed a smartphone application delivering digital brief behavioral treatment for insomnia (BBT-I). We also designed a four-week program integrating the app with light therapy (LT) via wearable glasses named \u201cDigital BBT-I + LT\u201d. This randomized controlled trial will evaluate the efficacy of digital BBT-I with LT and digital BBT-I alone compared with a waitlist control group. Methods: This three-arm parallel-group randomized controlled trial will target young adults with insomnia symptoms and late chronotypes. Participants will be randomized to receive digital BBT-I with adjunctive LT, digital BBT-I alone, or a waitlist control condition. The primary outcome will be insomnia symptom severity, assessed using the Insomnia Severity Index. Evaluations will be conducted at baseline, weekly during the four-week intervention period (days 8, 15, 22, and 29), and at the 3-month follow-up. Discussion: Late chronotypes and insomnia significantly impair sleep and mental health in young adults. Despite the recognized importance of chronobiology-based treatments, they are rarely adopted as standard care. This highlights the need for scalable digital interventions, such as digital BBT-I. By rigorously assessing these strategies, this trial aims to provide clinical evidence regarding accessible interventions to improve sleep and mental health outcomes in this population.<\/jats:p>","DOI":"10.3390\/healthcare14101386","type":"journal-article","created":{"date-parts":[[2026,5,19]],"date-time":"2026-05-19T08:55:28Z","timestamp":1779180928000},"page":"1386","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Efficacy of Smartphone-Based Digital Brief Behavioral Treatment for Insomnia with Adjunct Light Therapy in Young Adults with Insomnia Symptoms and Late Chronotypes: A Three-Arm Randomized Controlled Trial Protocol"],"prefix":"10.3390","volume":"14","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-0809-2697","authenticated-orcid":false,"given":"Ryuji","family":"Furihata","sequence":"first","affiliation":[{"name":"Agency for Student Support and Disability Resources, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7661-6299","authenticated-orcid":false,"given":"Tomonari","family":"Shimamoto","sequence":"additional","affiliation":[{"name":"Department of Preventive Services, Kyoto University School of Public Health, Graduate School of Medicine, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-7495-8957","authenticated-orcid":false,"given":"Yukako","family":"Nakagami","sequence":"additional","affiliation":[{"name":"Agency for Student Support and Disability Resources, Kyoto University, Yoshida-honmachi, Sakyo-ku, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9919-6768","authenticated-orcid":false,"given":"Satoe","family":"Okabayashi","sequence":"additional","affiliation":[{"name":"Agency for Health, Safety and Environment, Kyoto University, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-0644-6129","authenticated-orcid":false,"given":"Kosuke","family":"Kiyohara","sequence":"additional","affiliation":[{"name":"Department of Food Science, Otsuma Women\u2019s University, Tokyo 102-8357, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Toshiki","family":"Akahoshi","sequence":"additional","affiliation":[{"name":"Shinjuku Sleep and Respiratory Clinic, KEISHINKINENKAI Medical Corporation, Tokyo 160-0023, Japan"},{"name":"Division of Respiratory Medicine, Department of Internal Medicine, Nihon University, Tokyo 101-8309, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4073-9945","authenticated-orcid":false,"given":"Yoshimitsu","family":"Takahashi","sequence":"additional","affiliation":[{"name":"Department of Implementation Science in Public Health, Kyoto University School of Public Health, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Taku","family":"Iwami","sequence":"additional","affiliation":[{"name":"Department of Preventive Services, Kyoto University School of Public Health, Graduate School of Medicine, Kyoto 606-8501, Japan"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,5,19]]},"reference":[{"key":"ref_1","unstructured":"American Academy of Sleep Medicine (2023). 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