Sleep, Mental Fatigue, and Performance in Students

Study overview

This is a prospective, observational, within-subject, repeated-measures, naturalistic case-crossover study involving physiotherapy and psychology students at LUDES Institute. The study focuses on how real-world academic demands (lectures and exams) interact with sleep, circadian rhythms, and mental fatigue to influence cognitive and physical performance. Each participant serves as their own control across three conditions: a baseline week without formal classes or exams, a typical theoretical class day, and, where applicable, an exam day.

The project is categorized as Category A (minimal risk and burden) under Swiss human research legislation and will be conducted in accordance with the Declaration of Helsinki, ICH-GCP (International Council for Harmonisation Good Clinical Practice), and applicable Swiss laws and guidelines.

Study objectives and hypotheses

The central objective is to characterize the psychobiological responses of physiotherapy and psychology students under varying academic pressures and schedules.

The study aims to:

Quantify changes in subjective mental fatigue, sleepiness, motivation, and objective cognitive and physical performance from before to after lectures and exams.

Evaluate how sustained cognitive demand across the university day affects psychomotor vigilance, executive control, and handgrip endurance.

Determine how sleep quantity and quality, as well as chronotype and time of day, moderate these responses.

Explore how the interaction between chronotype and timing of classes/exams relates to academic performance (exam grades) and perceived stress.

Key hypotheses include:

Longer classes and exam sessions will be associated with greater increases in mental fatigue, perceived effort, and sleepiness, and with reduced motivation and executive performance post-session; physical capacity is expected to show smaller decrements.

Students with sleep efficiency above 85% and nightly sleep duration above 7 hours will show greater resilience to mental fatigue, maintaining more stable reaction times and better cognitive performance than those with shorter or poorer-quality sleep.

Evening-type students will perform worse and feel sleepier during morning sessions compared with morning-type students, independently of total sleep duration, reflecting a chronotype × time-of-day interaction.

Mental fatigue will strongly impair cognitive tasks, while physical capacity (handgrip) will show relatively smaller declines.

Study design

The study uses a prospective, within-subject repeated-measures design with three main observation windows (T0, T1, T2).

Baseline/familiarization (T0):

A control week with no formal academic demands (no classes or exams). During this week, baseline psychometric, behavioral, and sleep profiles are collected, including overall sleep quality over the past 30 days and chronotype. Participants complete the Pittsburgh Sleep Quality Index (PSQI) and Morningness-Eveningness Questionnaire (MEQ), provide demographic and lifestyle information (e.g., caffeine use, napping, fitness), and undergo baseline assessments of mental fatigue, sleepiness, motivation, cognitive performance, and handgrip strength and endurance.

Class condition (T1):

A regular theoretical lecture session is used as the exposure. Pre- and post-class assessments are conducted in both morning and afternoon sessions (ideally before 09:00 and after 13:00 for morning, before 14:00 and after 17:00 for afternoon). The same battery as at baseline is administered, with added measurement of class duration.

Exam condition (T2):

An exam session, when feasible based on each student's timetable, is used as a high-stakes exposure. Pre- and post-exam measures parallel those in the class condition. Exam grades are collected as an indicator of academic achievement.

Across all conditions, assessments are scheduled twice in the morning and twice in the afternoon, yielding multiple pre/post evaluations per participant.

Study population and eligibility

Participants are physiotherapy and psychology students at LUDES Institute. The target sample size is 30 students, with an expected dropout of 10-15% after the start of experimental procedures.

Inclusion criteria:

Enrolled physiotherapy or psychology student at LUDES Institute, age 18 years or older, no self-reported major neurological disorders or conditions that would impair cognitive or physical testing.

Exclusion criteria (relevant to the specific study sessions):

Use of psychostimulants (e.g., caffeine, energy drinks) before or during scheduled study sessions, vigorous exercise prior to testing sessions, melatonin intake, recent travel involving more than 3 time zones or shift/part-time shift work, self-reported clinical sleep disorders, absence from more than 25% of total scheduled lesson time.

Recruitment and informed consent

Recruitment and screening are coordinated by the project leader and the DIMUSCHEL research team. Students are initially informed about the study at the end of a class by a member of the research staff. Those who express interest receive more detailed information in person. After verbal agreement, students are given an information sheet and a consent form (pre-signed by the project leader and provided in duplicate). They are allowed sufficient time to read, ask questions, and decide whether to participate.

Participation is voluntary, and students may withdraw at any time without consequences. No financial compensation is offered. Signed consent forms are collected and retained as part of the study records.

Interventions and procedures

This is an observational study with no experimental therapeutic intervention. The "procedures" consist of non-invasive questionnaires, cognitive tasks, physical tests, and sleep monitoring.

Cognitive assessments

Stroop task (Encephalapp):

A tablet-based Stroop task is administered in two modes: congruent (Stroop "off") and incongruent (Stroop "on"). In the congruent condition, participants identify the color of pound signs displayed in different colors; in the incongruent condition, they identify the font color of color words presented in mismatched ink (e.g., the word "green" printed in blue). The test includes six phases per condition, with approximately 60 trials in each condition. Response time (latency for correct responses) and accuracy (number of correct responses) are recorded, and results are averaged across trials. Each Stroop assessment takes about 5 minutes.

Subjective states (mental fatigue, sleepiness, effort, motivation)

Visual Analogue Scale for Mental Fatigue (VAS-MF):

A 0-100 mm visual analogue scale anchored by "none at all" and "maximal" is used. Participants answer "How mentally fatigued do you feel now?" after receiving a standardized definition and examples of mental fatigue. Scores are derived by measuring the distance from the 0-mm anchor to the participant's mark.

Karolinska Sleepiness Scale (KSS):

A 9-point scale ranging from "not sleepy at all" to "extremely sleepy" is used to assess sleepiness. The KSS is administered before sleep, upon waking, and before and after teaching (T1) or exams (T2).

Rating of Perceived Exertion (CR-10 scale):

An 11-point numerical scale (0-10) assesses perceived effort during the handgrip endurance test. The scale is applied every 30 seconds, where 0 indicates no effort and 10 indicates maximal perceived exertion.

Motivational States Scale:

A 15-item Likert-type scale capturing task engagement, distress, and worry is administered before and after teaching and exam sessions.

Physical performance

Handgrip Strength and Endurance (HGSE):

Maximal and endurance handgrip performance is assessed using a hydraulic dynamometer. For maximal strength, participants perform three maximal squeezes with the dominant hand while seated, with the elbow at 90 degrees and wrist in a neutral position. Each squeeze lasts 3 seconds with 60 seconds rest, and the average of three trials is used for analysis. For endurance, participants maintain 40% of their own maximal force as long as possible; time to task failure is recorded, where failure is defined as force dropping below 40% for more than three seconds. The overall test (including setup, three maximal trials, and endurance bout) takes about 8 minutes.

Sleep and circadian assessment

Actigraphy and sleep diaries:

Sleep is monitored with wrist actigraphy (MotionWatch 8) and daily sleep diaries. During baseline and class conditions, actigraphy is recorded for two weeks, with an additional week for the exam condition when applicable. Sleep diary entries include bedtime, wake time, nap duration, and nocturnal awakenings. Derived parameters include bedtime, get-up time, time in bed, sleep onset and offset, sleep efficiency, sleep latency, wake after sleep onset, total sleep time, immobility time, and fragmentation index. Upon waking, participants rate sleep quality on a 10-point Likert scale. If actigraphy cannot be used for all participants, a "full diary plus actigraphy subsample" strategy is employed.

Questionnaires:

Sleep quality over the past month is assessed with the PSQI (Pittsburgh Sleep Quality Index), and chronotype with the MEQ (Morningness-Eveningness Questionnaire). These instruments inform the analysis of how sleep history and circadian preference influence acute responses to classes and exams.

Assessment sequence and duration

To reduce carry-over and arousal effects, the assessment sequence at each session is fixed: VAS-MF (Visual Analogue Scale for Mental Fatigue), KSS (Karolinska Sleepiness Scale), Stroop task, Motivation (Motivational States Scale), Handgrip endurance with perceived effort.

This sequence ensures that subjective state ratings are collected before tasks that could alter them, that vigilance tasks precede more complex executive tasks, and that physical exertion is last to avoid sympathetic activation affecting cognitive measures. Total time per assessment session is approximately 20 minutes.

Outcomes

Primary outcome

Within-subject change in mental fatigue (VAS-MF; 0-100 mm) and cognitive performance (Stroop reaction time/accuracy) from pre- to post-session across baseline, class, and exam conditions.

Key secondary outcomes

Sleep and circadian metrics (actigraphy + diaries, KSS, PSQI, MEQ), Handgrip strength and endurance (including perceived exertion), Motivation (Motivational States Scale scores), Academic performance (exam grades), Perceived stress components and time-of-day effects.

Sample size and statistical analysis

An a priori power analysis using a repeated-measures framework indicated that 26 participants would provide approximately 81% power (alpha 0.05) to detect the expected interaction on mental fatigue (Time × Turn; pre/post × morning/afternoon). Allowing for about 10% attrition, 30 participants will be recruited.

Primary analyses will use mixed-effects models with students as random intercepts. Fixed effects will include Session (pre vs post), Condition (T0/T1/T2), Time of day (AM vs PM), class/exam duration, and sleep/circadian covariates (e.g., prior-night total sleep time, sleep efficiency, sleep latency, MEQ score), as well as interaction terms (e.g., Session × Duration, Session × Time of day, Session × MEQ). The models will estimate how academic load and timing, combined with sleep and chronotype, influence changes in psychobiological outcomes.

Missing data will be addressed by recruiting additional participants if necessary to maintain adequate power, and by using mixed-model approaches that can accommodate incomplete repeated measures.

Safety, risk, and ethics

The study involves only minimal risk procedures (questionnaires, non-invasive cognitive tasks, handgrip testing, and actigraphy). No drugs, devices, or radiation are used. The project is classified as Category A and adheres to the Declaration of Helsinki, ICH-GCP (International Council for Harmonisation Good Clinical Practice), and Swiss regulations.

Participation is voluntary, and withdrawal is allowed at any time. If participants withdraw after contributing data, their existing data may still be used in analyses in pseudonymized form, unless they request otherwise in line with applicable law.

Data management, confidentiality, and quality assurance

Data are captured in case report forms and electronic databases using unique participant codes. The key linking codes to identities is stored separately under restricted access, solely for purposes of follow-up assessments and longitudinal linkage. After the end of the study, data may be fully anonymized when feasible, and will be stored and destroyed according to institutional and legal requirements.

Confidentiality is safeguarded through coding, secure storage, and controlled access. Only authorized study staff will access identifiable information. Quality assurance measures include standardized training of assessors, fixed testing sequences, and use of validated instruments to ensure reliability and internal validity.