Healthy Diet, Sleep
Conditions
Keywords
Sleep quality, Walnuts, Body composition, Circadian rhythms
Brief summary
Walnuts have a unique nutritional profile, including the sleep-regulating hormone melatonin, tryptophan, and omega-3 fatty acids, the two latest nutrients involved in melatonin and serotonin synthesis. Although it has been claimed that walnuts may improve sleep, to the investigators' knowledge, no studies have been conducted to objectively determine the impact of walnut consumption on sleep and overall well-being. Therefore, this study aims to investigate the effect of daily walnut consumption on sleep parameters (such as quality and duration). Secondarily, it aims to investigate the impact of daily walnut consumption on body composition, eating behavior, and well-being.
Detailed description
The study to investigate the effect of daily walnut consumption on sleep quality will be conducted in an 18-week randomized crossover trial, in which participants will be initially assigned to intervention or control conditions for 8-weeks. After 2 weeks of washout, subjects will be crossed over to the alternate intervention and will continue for another 8 weeks. Note that throughout the whole study, each participant will attend 5 visits: 1 initial visit (baseline) and 2 visits in each one of the study conditions (intervention and control).
Interventions
OTHERControl
Participants will be asked to refrain from walnut intake and to follow an isocaloric meal plan that complies with the recommendations of a healthy Mediterranean-style eating pattern.
OTHERWalnut intake
Participants will be asked to consume walnuts along with an isocaloric meal plan that complies with the recommendations of a healthy Mediterranean-style eating pattern.
Sponsors
California Walnut Commission
University of Barcelona
Study design
Allocation
RANDOMIZED
Intervention model
CROSSOVER
Primary purpose
OTHER
Masking
NONE
Eligibility
Sex/Gender
ALL
Age
20 Years to 40 Years
Healthy volunteers
Yes
Inclusion criteria
* BMI 19-26 kg/m\^2 * Habitual moderate exercise level * No recent history of weight change exceeding 2.3kg (5lb) within the prior 3 months.
Exclusion criteria
* Nuts allergy * Any acute or chronic diseases * Smokers * Any drugs or supplementations * Any alimentary restrictions or specific diets * Being a shift or night workers * Being unable to give written informed consent.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Changes in urinary 6-sulphaoxymelatonin from baseline to week 4, 8, 14 and 18 | Week 4, 8, 14 and 18 | Quantified using urine Melatonin-Sulfate ELISA kit |
| Changes in sleep onset latency from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14 and 18 | Measured in hours of sleep with an actigraph (ActTrust, CONDOR, Brazil) |
| Changes in sleep efficiency from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14 and 18 | Calculated in percentage as the ratio of total sleep time (TST) to time in bed (TIB). Sleep efficiency (percent) = (TST/TIB)\*100 |
| Changes in wake after sleep onset (WASO) from baseline to weeks 4, 8, 14, and 18 | Week 4, 8, 14, and 18 | Measured in minutes of WASO with an actigraph (ActTrust, CONDOR, Brazil) |
| Changes in sleep duration from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14, and 18 | Measured in hours of sleep time with an actigraph (ActTrust, CONDOR, Brazil) |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| Changes in body mass index (BMI) from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14 and 18 | Calculated as weight (kg) divided by height (in squared meters), BMI= kg/m\^2 |
| Changes in body fat from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14 and 18 | Measured as the percentage of body fat with a body composition analyzer (Inbody 120, Korea) |
| Changes in weight circumference from baseline to weeks 4, 8, 14, and 18 | Weeks 4, 8, 14 and 18 | Measured midway between the lower rib margin and the iliac crest with the subject standing and wearing only underwear, at the end of gentle expiration with an anthropometric tape (CESCORF, Brazil) |
| Changes in eating behavior from baseline to weeks 8 and 18 | Weeks 8 and 18 | To evaluate changes in eating behavior, the Spanish version of the Food Cravings Questionnaire will be used (Cepeda-Benito et al, 2000). This questionnaire evaluates 10 dimensions of eating behavior: * Having Intentions and Plans to Consume Food * Anticipation of Positive Reinforcement that may Result from Eating * Anticipation of Relief from Negative States and Feelings as a Result of Eating * Lack of Control over Eating * Thoughts or Preoccupation with Food * Having Intentions and Plans to Consume Food * Craving as a Physiological State * Emotions that may be Experienced Before or During Food Cravings or Eating * Cues that may Trigger Food Cravings * Guilt from Cravings and/or for Giving in to Them For each subscale, scores range from 0 to 5, with higher scores indicating a stronger sensation of craving. |
| Changes in well-being from baseline to weeks 8 and 18 | Weeks 8 and 18 | Well-being will be measured with the Spanish version of the WHO-5 Well-being Index (Lucas-Carrasco et. al. 2012). Scores range from 0 to 100, with higher scores indicating higher well-being. |
Countries
Spain
Outcome results
None listed