This study will test whether an internet-based cognitive behavioral therapy for insomnia (ICBT-I) delivered through the Persian-language web program "Omid" can improve sleep in Persian-speaking adults with insomnia. Participants will be adults who have problems falling or staying asleep and meet diagnostic criteria for insomnia. Those who are eligible will be randomly assigned to either receive access to the Omid web-based CBT-I program or to a wait-list control group that will receive usual care during the study period. The Omid program provides weekly online modules with educational videos and texts about sleep and insomnia, sleep hygiene, stimulus control, sleep restriction, and cognitive techniques to manage unhelpful thoughts about sleep. Participants will complete questionnaires about insomnia severity, sleep quality, and daytime sleepiness before starting the program, after finishing the intervention, and at follow-up. The main goal is to see whether the Omid ICBT-I program reduces insomnia symptoms and improves overall sleep quality compared with the wait-list control group.

Insomnia is a common sleep disorder that can lead to impaired daytime functioning, reduced quality of life, and increased risk of physical and mental health problems. Cognitive behavioral therapy for insomnia (CBT-I) is recommended as a first-line treatment, but access to trained therapists and face-to-face services is often limited. Internet-based CBT-I programs may help to overcome these barriers by providing structured, evidence-based treatment remotely and at lower cost.

This randomized controlled trial will evaluate the effectiveness of "Omid," a Persian-language, internet-based CBT-I program for Persian-speaking adults with insomnia. The trial will use a parallel-group design with two arms: an intervention arm receiving Omid ICBT-I and a wait-list control arm receiving usual care during the study period. Adults aged 18 to 60 years who meet diagnostic criteria for insomnia disorder, can read and write Persian, and have access to the internet via a computer or smartphone will be recruited. Individuals with moderate to severe depression or anxiety, other untreated sleep disorders (such as sleep apnea or restless legs syndrome), substance abuse, or serious neurological or medical conditions will be excluded.

The Omid intervention consists of six weekly web-based sessions that participants are encouraged to complete at a pace of one session per week. Each session combines brief psychoeducational videos and reading materials, interactive exercises, and daily sleep diary completion. Session content covers introduction to insomnia and the CBT-I model, sleep hygiene, stimulus control, sleep restriction and adjustment of time in bed, management of worry and rumination, identification and modification of dysfunctional beliefs about sleep, review of progress, and relapse prevention planning. An optional "Calm Mind" module provides guided relaxation and mindfulness audio tracks, neutral bedtime stories, and soothing environmental sounds to help reduce pre-sleep arousal. The platform also offers additional written psychoeducational materials to deepen understanding of insomnia and CBT-I techniques. Adherence is supported through daily and weekly homework tasks, automated reminders via SMS or email, and simple visual feedback on sleep diary completion and progress through the program. The intervention is primarily self-guided, with limited therapist contact available for brief clarification and adherence support when needed.

Eligible participants will complete baseline assessments and then be randomly assigned, using permuted block randomization with varying block sizes, in a 1:1 ratio to either the Omid ICBT-I group or the wait-list control group. Allocation concealment will be ensured using sequentially numbered, opaque, sealed envelopes. The study is open-label; however, the allocation sequence will be concealed from those enrolling participants until assignment.

Participants in the Omid ICBT-I group will receive access to the Omid web platform for a fixed intervention period. The program delivers weekly online modules that include educational videos and texts about sleep and insomnia, sleep hygiene recommendations, stimulus control strategies (for example, using the bed only for sleep and getting out of bed when unable to sleep), sleep restriction instructions to consolidate sleep, and cognitive techniques to identify and modify unhelpful beliefs and worries about sleep. The platform also provides homework exercises and self-monitoring tasks designed to support behavior change and adherence to the new sleep schedule. Participants in the wait-list control group will receive usual care during the study and will be offered access to the Omid program after completion of the final follow-up assessments.

Outcome measures will be collected at baseline (before randomization), immediately after the intervention period, and at follow-up. The primary outcomes are insomnia severity, sleep quality, and daytime sleepiness, assessed using the Insomnia Severity Index (ISI), the Pittsburgh Sleep Quality Index (PSQI), and the Epworth Sleepiness Scale (ESS), respectively. The main hypothesis is that participants assigned to the Omid ICBT-I program will show greater reductions in insomnia severity and improvements in sleep quality and daytime sleepiness compared with the wait-list control group at post-intervention and follow-up. The results of this study will provide evidence on the effectiveness of a culturally adapted, Persian-language internet-based CBT-I program for adults with insomnia.

Inclusion Criteria:

• Age between 18 and 60 years.
• Meets diagnostic criteria for insomnia disorder according to DSM-5, based on clinical interview or a validated screening procedure.
• Insomnia Severity Index (ISI) score ≥ 10, indicating at least subthreshold insomnia.
• Reports difficulty initiating or maintaining sleep or early-morning awakenings at least three nights per week for at least three months, with associated daytime impairment (e.g., fatigue, concentration problems, irritability).
• Able to read and understand Persian.
• Has regular access to the internet and a smartphone and/or computer to use the Omid web-based program.
• Willing and able to provide informed consent and to complete online questionnaires and daily sleep diaries.

Exclusion Criteria:

• Uncontrolled medical or neurological conditions that significantly interfere with sleep or require immediate treatment (e.g., untreated moderate-to-severe obstructive sleep apnea, uncontrolled epilepsy, unstable cardiac disease, advanced cancer).
• Current shift work or rotating work schedules that regularly disrupt nighttime sleep.
• Pregnancy.
• Participation in another clinical trial or research study that could affect sleep during the study period.
• Ongoing structured psychotherapy specifically targeting insomnia or other major psychiatric conditions within the past 6 months.
• Current major depressive disorder or other severe psychiatric disorder (e.g., bipolar disorder, schizophrenia, psychotic disorders), as determined by clinical assessment or structured interview.
• Evidence of problematic substance use, such as heavy alcohol use (more than approximately 3 standard drinks per day on most days of the month) or frequent misuse of recreational drugs (e.g., cannabis use more than once per week), in the judgment of the investigators.
• Active suicidal ideation or behavior requiring urgent clinical intervention.
• Primary diagnosis of another untreated sleep disorder (e.g., restless legs syndrome, narcolepsy, circadian rhythm sleep-wake disorder) where insomnia is not the main problem.
• Having an infant or child under 2 years of age whose care regularly disrupts nighttime sleep, in the judgment of the investigators.