This trial aims to investigate whether morning bright light therapy can reduce the progression rate of idiopathic scoliosis in children and potentially prevent its de novo development.

Adolescent idiopathic scoliosis (AIS) is the most common pediatric spinal deformity, characterized by a lateral spinal curvature of ≥10° in the absence of congenital or neuromuscular abnormalities. Afflicting 3-4% of children worldwide, AIS emerges during the vulnerable period of puberty, yet its underlying etiology remains poorly understood. Adolescence is also associated with a gradual shift in circadian rhythm, characterized by an intrinsic phase delay and increased evening preference that coincides with pubertal development. Notably, our unpublished data reveal that the prevalence of evening chronotype among children with idiopathic scoliosis may reach 20-30%, significantly higher than in the general pediatric population. While circadian disruption is known to adversely affect bone metabolism, muscle mass, and postural control in adults, its impact on children-particularly those with circadian vulnerability-remains unexplored.

We hypothesize that the circadian phase delay and associated sleep disruption during the peripubertal period may represent a modifiable risk factor contributing to the onset or progression of spinal curvature. Bright light therapy is a well-established intervention for circadian rhythm sleep-wake disorders, capable of advancing the circadian phase and stabilizing sleep patterns.

This prospective, single-blind, randomized controlled trial will investigate the efficacy of bright light therapy in modifying the natural history of idiopathic scoliosis. Children with idiopathic scoliosis and a confirmed evening chronotype will be randomized into one of two groups. The Intervention Group will receive a combination of morning bright light exposure and standardized sleep hygiene education. Participants will be instructed to wear a portable light therapy device (480nm, 400LUX) for 15-30 minutes each weekday morning immediately upon waking, for a duration of 6 months. The Control Group will receive identical sleep hygiene education but no light therapy device, serving as an active comparator to control for the effects of increased health awareness and behavioral recommendations. To ensure adherence, the intervention group will receive regular telephone follow-ups to monitor device usage, address challenges, and encourage compliance; flexible adjustment of exposure timing (e.g., mid-morning) will be permitted if morning adherence proves difficult.

For all participants with scoliosis, routine follow-up visits with radiographic assessment will be scheduled at 6-month intervals for at least 24 months to evaluate curve progression. Additionally, children with an evening chronotype but without scoliosis at baseline will also be randomized to the same intervention arms and will undergo annual scoliosis screening as part of an ongoing provincial health initiative. This study may identify a safe, non-pharmacological intervention targeting circadian rhythm as a novel approach to scoliosis management.

Inclusion Criteria:

1. Age between 10 and 15 years.
2. Classified as evening chronotype based on the reduced Horne-Östberg Morningness-Eveningness Questionnaire (rMEQ), defined as a score < 12.
3. Has undergone radiographic evaluation (standing full-spine X-ray) for idiopathic scoliosis at the initial clinic visit.
4. Skeletally immature (Risser sign 0-3) with a major Cobb angle < 40 degrees at baseline.
5. Written informed consent/assent provided by the participant and legal guardian.
6. Willing and able to comply with the study protocol, including device use and scheduled follow-ups.

Exclusion Criteria:

1. Plans to relocate outside the study area within the next 24 months.

2. Use of medications that may interfere with circadian rhythm within the past 3 months (e.g., lithium, exogenous melatonin, melatonergic antidepressants).

3. Trans-meridian travel across at least two time zones within the past 3 months or anticipated during the study period.

4. Presence of any eye disease (e.g., glaucoma, retinal disease, macular degeneration) that could be exacerbated by or interfere with light therapy.

5. Clinically diagnosed sleep disorder (e.g., narcolepsy, restless legs syndrome) or prominent medical condition known to interfere with sleep continuity and quality (e.g., moderate-to-severe eczema).

6. Severe chronic health conditions that could confound study outcomes, including but not limited to:

   • Known syndromic, neuromuscular, or congenital musculoskeletal causes of scoliosis.
   • History of spine surgery or significant spinal trauma.
   • Spinal tumor.
   • Leg length discrepancy > 20 mm.
   • Other severe chronic diseases (e.g., poorly controlled diabetes, chronic liver or renal disease, malabsorption syndromes).
   • Severe obesity (body mass index z-score ≥ 3).

The radiologists measuring Cobb angles will be blinded to treatment allocation.