Insomnia exacerbates pain sensitivity and impairs physiological recovery from acute musculoskeletal pain. Repetitive transcranial magnetic stimulation (rTMS) has emerged as a promising non-invasive neuromodulation intervention to alleviate pain and modulate central sensory processing. However, whether rTMS can effectively mitigate insomnia-induced pain hyperalgesia and accelerate the recovery trajectory of acute musculoskeletal pain remains unclear, as does the optimal neuroanatomical stimulation target. Building upon an established experimental pain model, this randomized, sham-controlled study aims to evaluate the restorative effects of three distinct rTMS interventions - targeting the left primary motor cortex (L M1), the right dorsolateral prefrontal cortex (R DLPFC), and a sham condition - on individuals experiencing insomnia. Following a standardized eccentric exercise protocol to induce muscle soreness, participants will receive three sessions of the allocated rTMS intervention at 0, 24, and 48 hours post-exercise. Pain sensitivity, recovery dynamics, and quantitative sensory testing (QST) metrics will be continuously monitored across the recovery timeframe. The findings from this trial will clarify the therapeutic efficacy of rTMS in modulating acute pain under insomnia states and identify the target-specific mechanisms of cortical stimulation, offering evidence-based non-invasive interventions for musculoskeletal pain management.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
30
High-frequency stimulation (10 Hz) will be delivered over left M1 at 90% RMT, consisting of 50 pulses per train, a 25-second inter-train interval, and 30 trains per session, yielding a total of 1500 pulses over 15 minutes.
Low-frequency stimulation (1 Hz) will be applied over right DLPFC-rTMS at 90% RMT, with 150 trains of 10 pulses per session, a 2-second inter-train interval, and a total of 1500 pulses over 30 min.
Sham stimulation will be administered using identical parameters but delivered via the sham coil, which reproduces the auditory and somatosensory sensations of active rTMS without inducing cortical stimulation.
The Hong Kong Polytechnic University
Hong Kong, Hong Kong
RECRUITINGMuscle damage severity: Muscle pain
Muscle pain will be measured using an 11-point NRS, with 0 representing "no pain" and 10 indicating "worst imaginable pain". The Outcome will be recorded at rest, during a reach for the floor with knees straight, and during a validated hamstring provocative manoeuvre, the "taking-off shoe" test.
Time frame: Day 0 to Day 14
Muscle damage severity: Muscle soreness
Muscle soreness will be measured by an 7-point Likert scale, with 0= A complete absence of soreness," 1 = "A light soreness in the muscle felt only when touched/a vague ache," 2 = "A moderate soreness felt only when touched/a slight persistent pain," 3 = "A light muscle soreness when walking up and down stairs," 4 = "A light muscle soreness when walking on flat surface," 5 = "A moderate muscle soreness, stiffness, or weakness when walking," 6 = "A severe muscle soreness, stiffness, or weakness that limits my ability to move."
Time frame: Day 0 to Day 14
Pain sensitivity: Thermal pain threshold
Thermal thresholds will be measured with a 30 × 30 mm thermode (TSA 2, Medoc Ltd., Ramat Yishai, Israel). The thermode will be placed gently on the skin without causing deformation. Using the method of limits, temperature will increase or decrease at 1℃/second within a 0 - 51℃ range, with a baseline temperature of 32℃. Participants will press the stop button when the thermal sensation first becomes painful. The mean value of five consecutive trials will be used in the analysis.
Time frame: Day 7 and Day 9
Pain sensitivity: Mechanical pain threshold
Mechanical pain threshold will be evaluated using standardised weighted pinprick stimulators (MRC System GmbH, Heidelberg, Germany) with a 0.25mm flat contact area. Seven fixed intensities (8 mN - 512 mN) will be applied. The final threshold will be calculated as the geometric mean of the ascending and descending stimulus intensities from five series.
Time frame: Day 7 and Day 9
Pain sensitivity: Pressure pain threshold (PPT)
Pressure pain threshold (PPT) will be assessed with a digital pressure algometer (Medoc Ltd., Ramat Yishai, Israel) equipped with a 1 cm2 rubber probe. Pressure will be applied at 30 kPa per second until participants perceive pain. Three trials will be performed, and the mean scores will be calculated to determine the PPT.
Time frame: Day 7 and Day 9
Pain sensitivity: Temporal summation of mechanical pain (TSP-M)
The pinprick stimulator will assess TSP-M at 256 mN. Ten stimuli will be delivered at 1-second intervals over a 1 cm2 area. Pain intensity will be rated on an 11-point NRS after the first and the 10th stimuli. If the NRS pain rating remains 0 out of 10 for three consecutive 256 mN stimuli, intensity will be increased to 512 mN, and the trial will be repeated. TSP-M will be calculated as the NRS difference between the first stimulus and the 10th stimulus.
Time frame: Day 7 and Day 9
Pain sensitivity: Temporal summation of heat pain (TSP-H)
TSP-H will be measured with a 9 cm2 thermode (TSA 2, Medoc Ltd., Ramat Yishai, Israel). Two sequences of 10 heat pulses at 46 ℃ and 48 ℃ will be delivered with a 5-minute interval. Each pulse has a 0.5 s duration and will be delivered from a 40 ˚C baseline at a 13°C/s ramp rate and 2.5 s interstimulus interval. The participant will rate pain intensity on an 11-point NRS after each stimulus. TSP-H will be defined as the NRS difference between the 10th stimulus and the first stimulus for each temperature.
Time frame: Day 7 and Day 9
Pain sensitivity: Conditioned pain modulation (CPM)
CPM will be evaluated using a noxious conditioning stimulus (CS) and a test stimulus (TS). The CS will be contact heat applied to the dominant volar forearm between the distal third of the forearm and the ulnar styloid. Temperature will be set 1.1 °C above the participant's HPT for 120s, starting from 32 ℃ with an 8°C/s ramp using the TSA 2 device (Medoc Ltd., Ramat Yishai, Israel). During the CPM assessment, if participants could not tolerate the CS (i.e., pain intensity over 8 on the11-point NPRS) or if they reported a pain intensity below 4 on the 11-point NPRS, the temperature of the CS will be adjusted to ensure a safe and adequate stimulus intensity. The TS will be applied to the thenar eminence of the non-dominant hand using a pressure algometer (Medoc Ltd., Ramat Yishai, Israel) to determine PPT before and immediately after the CS. The CPM effect will be calculated by subtracting the PPT measured before the CS from the PPT measured after the CS.
Time frame: Day 7 and Day 9
Sleep Questionnaires: the Insomnia Severity Index (ISI)
The ISI is a 7-item self-report questionnaire assessing the nature, severity, and impact of insomnia. Each item is rated on a 5-point Likert scale (0 to 4). The total score ranges from 0 to 28, with higher scores indicating greater severity of insomnia.
Time frame: Day 0 and Day 7
Sleep Questionnaires: The Pittsburgh Sleep Quality Index (PSQI)
The PSQI is a 19-item self-report questionnaire that evaluates sleep quality and disturbances over a 1-month time interval. It generates seven component scores: subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleep medication, and daytime dysfunction. Each component is scored from 0 to 3. The sum of these seven component scores yields a global PSQI score ranging from 0 to 21, where higher scores indicate poorer sleep quality.
Time frame: Day 0 and Day 7
Sleep diary: Total Sleep Time
Assessed using a daily consensus sleep diary. Total Sleep Time is calculated as the total time spent asleep, derived from the total time in bed (bedtime to rise time) minus sleep onset latency and wake after sleep onset. Higher values indicate longer sleep duration.
Time frame: Day 0 to Day 14
Sleep diary: Sleep Onset Latency (SOL)
Assessed using a daily consensus sleep diary. Sleep Onset Latency is the estimated time (in minutes) it takes to fall asleep after turning off the lights. Lower values indicate better sleep onset.
Time frame: Day 0 to Day 14
Sleep diary: Wake After Sleep Onset (WASO)
Assessed using a daily consensus sleep diary. WASO is calculated as the total duration of wakefulness (in minutes) between initial sleep onset and final awakening, derived from the number of night awakenings multiplied by their average duration. Lower values indicate better sleep continuity.
Time frame: Day 0 to Day 14
Sleep diary: Sleep Efficiency (SE)
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Assessed using a daily consensus sleep diary. Sleep Efficiency is calculated as the percentage of time in bed spent asleep: \[(Total Sleep Time / Total Time in Bed) × 100\]. Total Sleep Time is derived from total time in bed (time between bedtime and rise time) minus sleep onset latency and nocturnal wakefulness (calculated from the number and duration of night awakenings). Scores range from 0% to 100%, with higher percentages indicating better sleep quality.
Time frame: Day 0 to Day 14
Actigraphy: Total Sleep Time (TST)
Measured objectively using a wrist-worn ActiGraph accelerometer. Sleep Onset Latency is defined as the period of time (in minutes) between the initial bedtime (lights out) and the onset of continuous sleep detected by the algorithm. Lower values indicate faster sleep onset and better sleep initiation.
Time frame: Day 0 to Day 14
Actigraphy: Sleep Onset Latency (SOL)
Measured objectively using a wrist-worn ActiGraph accelerometer. Sleep Onset Latency is defined as the period of time (in minutes) between the initial bedtime (lights out) and the onset of continuous sleep detected by the algorithm. Lower values indicate faster sleep onset and better sleep initiation.
Time frame: Day 0 to Day 14
Actigraphy: Wake After Sleep Onset (WASO)
Measured objectively using a wrist-worn ActiGraph accelerometer. WASO is defined as the total number of minutes spent awake after initial sleep onset and before final awakening, as determined by epoch-by-epoch movement counts. Lower values indicate better sleep continuity and fewer night awakenings.
Time frame: Day 0 to Day 14
Actigraphy: Sleep Efficiency (SE)
Measured objectively using a wrist-worn ActiGraph accelerometer. Sleep Efficiency is calculated as the percentage of time in bed spent asleep: \[(Total Sleep Time / Total Time in Bed) × 100\]. Values range from 0% to 100%, with higher percentages indicating better sleep quality and efficiency.
Time frame: Day 0 to Day 14
Psychological measurement: Depression, Anxiety, and Stress Scale (DASS-21)
Assessed using the 21-item Depression Anxiety Stress Scales (DASS-21). The instrument consists of three 7-item subscales measuring depression, anxiety, and stress. Each item is rated on a 4-point Likert scale ranging from 0 ("did not apply to me at all") to 3 ("applied to me very much or most of the time"). Sum scores for each subscale are calculated and multiplied by 2 to yield total scores ranging from 0 to 42 for each dimension (Depression: 0-42, Anxiety: 0-42, Stress: 0-42), with a total overall score ranging from 0 to 126. Higher scores indicate greater levels of psychological distress/severity.
Time frame: Day 0 to Day 14
Psychological measurement: Pain Catastrophizing Scale (PCS)
Assessed using the 13-item Pain Catastrophizing Scale (PCS) to evaluate catastrophic thoughts and feelings associated with pain (comprising rumination, magnification, and helplessness subscales). Each item is rated on a 5-point Likert scale from 0 ("not at all") to 4 ("all the time"). The total score ranges from 0 to 52, with higher scores indicating higher levels of pain catastrophizing.
Time frame: Day 0 to Day 14
Psychological measurement: Fear of Pain Questionnaire (FPQ-9)
Assessed using the 9-item short form of the Fear of Pain Questionnaire (FPQ-9) to assess fear of different painful experiences across severe pain, minor pain, and medical pain domains. Each item is rated on a 5-point Likert scale from 1 ("not at all") to 5 ("extreme"). The total score ranges from 9 to 45, with higher scores indicating greater fear of pain.
Time frame: Day 0 to Day 14
Psychological measurement: Tampa Scale for Kinesiophobia (TSK-11)
Assessed using the 11-item Tampa Scale for Kinesiophobia (TSK-11) to evaluate fear of movement or (re)injury. Each item is scored on a 4-point Likert scale ranging from 1 ("strongly disagree") to 4 ("strongly agree"). The total score ranges from 11 to 44, with higher scores indicating greater fear of movement/kinesiophobia.
Time frame: Day 0 to Day 14
Physical Activity Level: International Physical Activity Questionnaire - Short Form (IPAQ-SF)
Assessed using the 7-item International Physical Activity Questionnaire - Short Form (IPAQ-SF). The questionnaire measures the duration (minutes) and frequency (days) of walking, moderate-intensity activities, and vigorous-intensity activities performed over the last 7 days. Total physical activity volume is calculated as MET-minutes per week (MET-min/week) using standardised MET energy expenditure values: Walking = 3.3 METs, Moderate PA = 4.0 METs, and Vigorous PA = 8.0 METs. The total score is the sum of (METs × minutes × days) across all three domains, with scores starting from 0 and no strict upper limit. Higher scores indicate higher levels of overall physical activity.
Time frame: Day 0 to Day 14