1.
Effects of mental contrasting on sleep and associations with stress: A randomized controlled trial.
Schmidt, LI, Neubauer, AB, Stoffel, M, Ditzen, B, Schirmaier, J, Farrenkopf, C, Sieverding, M
Journal of health psychology. 2023;28(11):1057-1071
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Insufficient sleep is a widespread problem. For adults between 18 and 64 years, the National Sleep Foundation generally recommends a range of nightly sleep duration from 7 to 9 hours. The aim of this study was to test a self-regulatory intervention based on mental contrasting with implementation intentions (MCII) against the effects of sleep hygiene information only. This study was a single-blinded, randomised controlled trial with daily/nightly assessments in a baseline-week and analog daily/nightly assessments in a post-intervention week. Participants were randomly assigned to one of the two groups. Results indicated an increase in sleep quality and subjective (but not objective) sleep duration from baseline to post-intervention period. Additionally, regarding subjective stress, associations with daily sleep parameters were largely confirmed. Authors conclude that future research should include booster sessions and evaluate MCII effects in the longer run. Furthermore, a better understanding of the causes regarding insufficient sleep among specific target groups and their degree of controllability is required to develop individually targeted interventions.
Abstract
Mental contrasting with implementation intentions (MCII) has been successfully applied to improve health-related behaviors (e.g. exercise). We explored its effectiveness to improve sleep outcomes beyond effects of sleep hygiene (SH) information, and investigated associations with stress. Eighty university employees (mean age: 29.6, SD = 4.5) were randomized to either a MCII + SH or a SH-only condition. During a baseline-week and a post-intervention week, sleep duration (Fitbit Alta and self-report), sleep quality, and stress were assessed daily and saliva was collected to assess the cortisol awakening response (CAR). In total, self-reported sleep quality and duration increased, but there was no meaningful condition*week interaction for sleep parameters or CAR. Higher average stress was associated with shorter sleep duration and lower sleep quality. Within-person, days with higher stress were followed by nights with lower sleep quality. Despite overall improvements, effects of MCII were not confirmed. MCII might be less effective to improve behaviors which are less controllable.
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Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial.
Hidese, S, Ogawa, S, Ota, M, Ishida, I, Yasukawa, Z, Ozeki, M, Kunugi, H
Nutrients. 2019;11(10)
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L-theanine (γ-glutamylethylamide) is a unique non-protein amino acid found in green tea (Camellia sinensis), a widely consumed beverage associated with human health. The aim of this study was to examine the effects of four weeks L-theanine administration (200 mg/day, four weeks) in a healthy population, i.e., individuals without any major psychiatric disorder. This study is a randomized, placebo-controlled, crossover, and double-blind trial. The study enrolled thirty individuals (n = 9 men and n = 21 women). Participants received either an enzymatic synthetic product L-theanine or placebo tablets who had to orally self-administer before sleep each night for four weeks. Results show that four weeks L-theanine administration has positive effects on stress-related symptoms and cognitive function in a healthy population. Furthermore, the reduction in sleep quality problems (disturbances in sleep latency, sleep disturbance and use of sleep medication) was greater in the L-theanine administration compared to the placebo administration, while verbal fluency, especially letter fluency, was improved in the L-theanine administration among individuals who showed relatively low performance at pre-treatment. Authors conclude that L-theanine may be a suitable nutraceutical ingredient for improving mental conditions in a healthy population.
Abstract
This randomized, placebo-controlled, crossover, and double-blind trial aimed to examine the possible effects of four weeks L-theanine administration on stress-related symptoms and cognitive functions in healthy adults. Participants were 30 individuals (nine men and 21 women; age: 48.3 ± 11.9 years) who had no major psychiatric illness. L-theanine (200 mg/day) or placebo tablets were randomly and blindly assigned for four-week administration. For stress-related symptoms, Self-rating Depression Scale, State-Trait Anxiety Inventory-trait, and Pittsburgh Sleep Quality Index (PSQI) scores decreased after L-theanine administration (p = 0.019, 0.006, and 0.013, respectively). The PSQI subscale scores for sleep latency, sleep disturbance, and use of sleep medication reduced after L-theanine administration, compared to the placebo administration (all p < 0.05). For cognitive functions, verbal fluency and executive function scores improved after L-theanine administration (p = 0.001 and 0.031, respectively). Stratified analyses revealed that scores for verbal fluency (p = 0.002), especially letter fluency (p = 0.002), increased after L-theanine administration, compared to the placebo administration, in individuals who were sub-grouped into the lower half by the median split based on the mean pretreatment scores. Our findings suggest that L-theanine has the potential to promote mental health in the general population with stress-related ailments and cognitive impairments.