Obesity is frequently associated with sleep disturbances, including poor sleep quality, insomnia symptoms, daytime sleepiness, and obstructive sleep apnea. Metabolic surgery is an effective treatment for obesity and may improve several sleep-related outcomes, but the long-term change in sleep quality after surgery is not well understood. Most previous studies have relied on questionnaires or single-night measurements, which may not fully reflect sleep patterns in daily life.

The SLEEP-BAM study is an observational longitudinal cohort study in adults scheduled for primary metabolic surgery at Catharina Hospital Eindhoven, the Netherlands. Participants will complete two home-based sleep measurement periods: one before surgery and one approximately 1 year after surgery. During each period, participants will wear two wearable devices for 5 consecutive nights: a Garmin Index Sleep Monitor and a viQtor research device. Participants will also complete sleep questionnaires and a daily sleep diary.

The main aim is to evaluate the change in objective sleep quality from before surgery to 1 year after surgery, measured using the Garmin Sleep Score. Secondary aims include evaluating changes in sleep duration, sleep efficiency, sleep timing, sleep regularity, oxygen saturation, heart rate variability, subjective sleep quality, daytime sleepiness, anxiety and depression symptoms, and quality of life. The study will also explore whether changes in sleep quality are associated with postoperative weight loss.

The study does not change the standard surgical treatment. Participants undergo metabolic surgery as part of routine care, and the research procedures consist only of sleep monitoring, questionnaires, and sleep diaries.

The SLEEP-BAM study is a single-center, within-subject longitudinal observational cohort study designed to evaluate sleep quality before and after primary metabolic surgery. The study will be conducted at Catharina Hospital Eindhoven, the Netherlands, a high-volume center for metabolic surgery.

Sleep disturbances are common in patients with obesity and may include poor sleep quality, insomnia symptoms, excessive daytime sleepiness, disrupted sleep timing, and obstructive sleep apnea. In routine metabolic surgery care, sleep evaluation is often focused mainly on obstructive sleep apnea screening, while other aspects of sleep are less frequently assessed. Metabolic surgery may improve sleep quality through weight loss, improvement of obesity-related comorbidities, and changes in metabolic health, but the longitudinal trajectory of sleep quality after surgery remains insufficiently understood.

Participants will be adults scheduled for primary metabolic surgery, including Roux-en-Y gastric bypass, sleeve gastrectomy, and, if performed within standard care, one-anastomosis gastric bypass. Revisional bariatric procedures are excluded. The study does not assign participants to a treatment or intervention. Surgery is performed as part of routine clinical care, independent of study participation.

Each participant will undergo two measurement periods. The first measurement period will take place before surgery, between 3 months and 2 weeks preoperatively. The second measurement period will take place approximately 1 year postoperatively. The 1-year postoperative measurement was chosen to align with the period in which substantial postoperative weight loss has usually occurred and with standard follow-up in the metabolic surgery care pathway.

During each measurement period, participants will wear two devices at home for 5 consecutive nights. The Garmin Index Sleep Monitor will be used to collect consumer-grade sleep outcomes, including the Garmin Sleep Score, total sleep time, sleep efficiency, sleep latency, nocturnal awakenings, sleep stages, and sleep timing parameters. The viQtor research device will be used to collect physiological signals, including photoplethysmography-based parameters such as oxygen saturation and heart rate variability, as well as raw photoplethysmography signals for exploratory analysis.

A valid night is defined as a night with at least 4 hours of usable recording during the participant's sleep period, based on the sleep diary and/or device-detected sleep period. At least 3 valid nights are required per measurement period. Evening wake-time recordings before sleep onset alone are not sufficient to define a valid night.

The primary outcome is the change in Garmin Sleep Score from preoperative baseline to 1 year after metabolic surgery. The Garmin Sleep Score is a device-derived composite score ranging from 0 to 100. It reflects several sleep-related aspects, including sleep duration, sleep stages, restlessness, and related metrics. The score is used as a pragmatic longitudinal measure of sleep quality in the home setting and is not considered equivalent to polysomnography or a diagnostic measure of sleep disorders.

Secondary outcomes include changes in objective sleep parameters, such as total sleep time, sleep efficiency, sleep latency, percentage of rapid eye movement sleep, nocturnal awakenings, peripheral oxygen saturation, heart rate variability, bedtime, wake time, mid-sleep time, sleep timing variability, and sleep regularity. Subjective sleep outcomes include the Pittsburgh Sleep Quality Index, Epworth Sleepiness Scale, Hospital Anxiety and Depression Scale, and sleep diary-derived parameters. Quality of life will be assessed using the OBESI-Q. Clinical outcomes include postoperative weight loss, expressed as percentage total weight loss.

The study will compare subjective sleep reports with objective wearable-derived sleep measures. It will also explore the association between changes in sleep quality and postoperative weight loss, while considering clinical variables such as age, sex, baseline body mass index, type of surgery, comorbidities, medication use, and quality of life. An exploratory analysis of raw photoplethysmography signals from the viQtor device will assess signal quality and examine whether derived research features correlate with Garmin sleep metrics. This exploratory analysis is intended as an early step toward potential development of sleep-related parameters and is not intended for diagnostic validation.

The planned sample size is 50 participants. The sample size was based on a paired within-subject comparison for the primary outcome, with an assumed moderate effect size. The target sample size includes an allowance for incomplete wearable recordings, insufficient valid nights, and loss to follow-up.

The study has received ethical approval from Medical Research Ethics Committees United under registration number R26.043. Participants will provide written informed consent before any study-specific procedures are performed. Participation is voluntary and withdrawal from the study will not affect standard medical care.

Inclusion Criteria:

• Age 18 years or older.
• Body mass index (BMI) of 40 kg/m² or higher, or BMI of 35 kg/m² or higher with obesity-related comorbidities.
• Scheduled for primary metabolic surgery, including Roux-en-Y gastric bypass, sleeve gastrectomy, or, if performed within standard care, one-anastomosis gastric bypass.
• Willing and able to wear wearable devices for 5 consecutive nights during both study measurement periods.
• Willing and able to complete sleep questionnaires and a daily sleep diary.
• No shift-based or irregular night-shift work schedule that could interfere with sleep measurements.
• Able and willing to provide written informed consent.

Exclusion Criteria:

• Revisional bariatric procedure.
• Diagnosed obstructive sleep apnea currently treated with continuous positive airway pressure (CPAP) or bilevel positive airway pressure (BiPAP).
• High clinical suspicion of obstructive sleep apnea during the standard preoperative work-up requiring further diagnostic evaluation or treatment.
• Chronic preoperative use of medications that may significantly alter sleep quality, including benzodiazepines, zolpidem, or other sedatives or sleep aids.
• Unable to complete the study procedures or comply with wearable device use, questionnaires, or sleep diary completion.

Adults with obesity scheduled for primary metabolic surgery at Catharina Hospital Eindhoven, the Netherlands. Eligible participants will undergo Roux-en-Y gastric bypass, sleeve gastrectomy, or, if performed within standard care, one-anastomosis gastric bypass. Participants will complete home-based sleep monitoring before surgery and approximately 1 year after surgery.

Individual participant data will not be made publicly available because of participant privacy, GDPR requirements, and the limited sample size of this single-center study. Study data will be stored as coded/pseudonymized data on secure, access-restricted systems at Catharina Hospital Eindhoven. Only authorized members of the research team will have access to the study data. Technical device data may be shared with SmartQare only as described in the study protocol and without directly identifiable participant information.