This randomized, triple-blind, placebo-controlled clinical trial aims to evaluate the effects of daily saffron extract supplementation (30 mg/day) for six weeks on objective and subjective sleep quality in middle-aged adults with mild-to-moderate sleep disturbances. Secondary outcomes include heart rate variability, cognitive processing speed, emotional state, perceived health status, and biochemical stress markers.
Sleep disturbances are highly prevalent in middle-aged adults and are associated with impaired daytime functioning, increased cardiometabolic risk, and reduced quality of life. Pharmacological treatments may be effective but are often associated with adverse effects and dependency risk. Saffron (Crocus sativus L.) contains bioactive compounds such as crocins and safranal, which may modulate neurotransmitter systems involved in sleep regulation, including serotonin, dopamine, and GABA pathways. Eighty middle-aged adults with mild-to-moderate sleep disturbances will be randomly assigned to receive either 30 mg/day of standardized saffron extract or placebo for six weeks. Sleep will be objectively assessed using wrist-worn accelerometry over 14 days before and during the final weeks of intervention. Subjective sleep quality will be evaluated using validated questionnaires. The study follows CONSORT guidelines and will be conducted in accordance with the Declaration of Helsinki and Good Clinical Practice standards.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
80
Participants will receive 30 mg/day of standardized saffron extract (≥3% crocins; ≥2% safranal) for six weeks. Capsules will be taken once daily, one hour before bedtime.
Participants will receive identical capsules containing maltodextrin and excipients for six weeks, taken once daily one hour before bedtime.
Universidad de Granada
Granada, Granada, Spain
RECRUITINGObjective Sleep Efficiency (%)
Measured by wrist actigraphy over 14 consecutive days before intervention and during weeks 5-7 of supplementation.
Time frame: Baseline and Week 6
Total Sleep Time (hours)
Objectively measured total sleep time (in hours) assessed using wrist-worn triaxial accelerometry over 14 consecutive days. Data will be processed using validated algorithms integrating movement patterns and sleep diaries.
Time frame: Baseline and Week 6
Wake After Sleep Onset (minutes)
Wake After Sleep Onset (WASO), defined as the total number of minutes awake after initial sleep onset, measured objectively by wrist actigraphy over 14 consecutive days.
Time frame: Baseline and Week 6
Sleep Latency (minutes)
Sleep latency, defined as the time (in minutes) from reported bedtime to sleep onset, measured objectively using wrist-worn accelerometry and participant sleep logs.
Time frame: Baseline and Week 6
Pittsburgh Sleep Quality Index (PSQI) Score
Subjective sleep quality assessed using the Pittsburgh Sleep Quality Index (PSQI), a validated questionnaire that evaluates sleep quality over the previous month. Total score ranges from 0 to 21, with higher scores indicating poorer sleep quality.
Time frame: Baseline, Week 4, and Week 6
Insomnia Severity Index (ISI) Score
Severity of insomnia symptoms assessed using the Insomnia Severity Index (ISI). Total score ranges from 0 to 28, with higher scores indicating greater insomnia severity.
Time frame: Baseline, Week 4, and Week 6
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Epworth Sleepiness Scale (ESS) Score
Daytime sleepiness assessed using the Epworth Sleepiness Scale (ESS). Total score ranges from 0 to 24, with higher scores indicating greater daytime sleepiness.
Time frame: Baseline, Week 4, and Week 6
Heart Rate Variability (RMSSD and SDNN)
Cardiac autonomic modulation assessed through heart rate variability (HRV) analysis under resting conditions. Time-domain parameters include RMSSD (root mean square of successive differences) and SDNN (standard deviation of normal-to-normal intervals), measured during a 5-minute stable segment.
Time frame: Baseline and Week 6
Emotional State (BDI-FS, STAI, PSS-10 Scores)
Emotional status assessed using validated psychometric instruments: Beck Depression Inventory-Fast Screen (BDI-FS) State-Trait Anxiety Inventory (STAI) Perceived Stress Scale (PSS-10) Higher scores indicate greater depressive symptoms, anxiety, and perceived stress, respectively.
Time frame: Baseline, Week 4, and Week 6
Health-Related Quality of Life (SF-36 Score)
Health-related quality of life assessed using the Short Form-36 Health Survey (SF-36), which evaluates physical and mental health domains. Scores are standardized from 0 to 100, with higher scores indicating better perceived health status.
Time frame: Baseline, Week 4, and Week 6
Biochemical Stress Markers (Cortisol, ACTH, Glucose, Insulin)
Biochemical markers related to stress and metabolic function, including serum cortisol, adrenocorticotropic hormone (ACTH), fasting glucose, and insulin levels, obtained from clinical records and laboratory analyses.
Time frame: Baseline and Week 6