Effects of L-Theanine and Hericium Erinaceus Gummies on Psychological, Cognitive, and Sleep Quality in University Students

Psychological outcomes were evaluated using the 21-item Depression, Anxiety, and Stress Scale (DASS-21) Scores for each subscale range from 0 to 21, with higher scores indicating greater levels of depression, anxiety, and stress (i.e., worse psychological outcomes).

Body weight was measured using a calibrated digital weighing scale (Inbody 230, South Korea) to the nearest 0.1 kg. Participants were instructed to remove shoes, heavy clothing, and personal items prior to measurement. Body mass index (BMI) was derived using the formula body weight (kg) divided by height squared (m2).

Height was measured using a portable stadiometer (SECA 213, Germany) to the nearest 0.1 cm. Height was assessed with participants standing upright, heels together, arms relaxed at the sides, and head positioned in the Frankfort horizontal plane. Body mass index (BMI) was derived using the formula body weight (kg) divided by height squared (m2).

Sleep quality was assessed using the Pittsburgh Sleep Quality Index (PSQI). The questionnaire consists of 19 self-rated items that assess seven components: subjective sleep quality, sleep latency, sleep duration, sleep efficiency, sleep disturbance, use of medication and daytime dysfunction. Each component is scored from 0 to 3, yielding a global score ranging from 0 to 21, with higher scores indicating poorer sleep quality. A global score >5 indicated poor sleep quality.

Physical activity levels were assessed using the International Physical Activity Questionnaire - Short Form. The questionnaire contains seven items quantifying the frequency (days per week) and duration (minutes per day) of walking, moderate-intensity activity, vigorous-intensity activity, and sedentary behaviour.

Responses were converted into metabolic equivalent task (MET)-minutes per week according to standardized IPAQ scoring guidelines. Participants were categorized into low (<600 MET-min/week), moderate (600-3000 MET-min/week), and high (>3000 MET-min/week) physical activity levels.

Dietary intake was assessed using a 24-hour dietary recall method. Participants reported all food and beverage consumption over the previous 24 hours, including portion size, preparation methods, meal timing, and eating location.

Executive function and inhibitory control were assessed using a standardized colour-word Stroop task administered in paper-based format. Participants completed a single list of incongruent colour-word stimuli and were instructed to name the ink colour while ignoring the written word. A brief practice trial was provided prior to testing. Total completion time (seconds) and number of errors were recorded, with faster completion and fewer errors indicating better performance.

Visuospatial memory was assessed using a 5 × 5 grid-based recall task adapted from established visuospatial memory paradigms. Participants were presented with a grid containing 10 everyday objects positioned in fixed locations and were given 30 seconds to memorize the arrangement. The stimulus was then removed, and participants were required to reproduce the object locations. One point was awarded for each correctly recalled location with higher score indicates better visuospatial memory

Cognitive processing speed and mental flexibility were assessed using the standard Trail Making Test Parts A and B. The test was administered in paper-based format. In Part A, participants connected numbers in ascending order, while Part B required alternating between numbers and letters. Time to completion (seconds) was recorded. Errors were corrected immediately, and timing continued until completion.