Sleep, Chronotype, and Prosocial Allocation Decisions (SCPAD)

Associations Between Sleep Quality, Circadian Timing, and Prosocial Allocation Decisions in Adults

This observational behavioural study examines whether individual differences in sleep quality, sleep timing, and chronotype are associated with prosocial allocation decisions in adults. Participants will complete self-report sleep and circadian questionnaires, including the Pittsburgh Sleep Quality Index and the Munich Chronotype Questionnaire, a 7-day sleep diary, and a brief computer-based Dictator Game allocation task.

The study does not involve sleep deprivation, sleep restriction, treatment, clinical diagnosis, medication, or medical devices. Participants will not be asked to change their sleep schedule. The Dictator Game decisions are hypothetical and do not affect participants' compensation. The study is intended to describe associations between naturally occurring sleep-related individual differences and behavioural allocation choices, not to diagnose or treat sleep or mental health conditions.

Study Overview

• Status: Not yet recruiting
• Conditions: Sleep Quality; Chronotype; Prosocial Decision-Making; Circadian Timing
• Intervention / Treatment: Other: Sleep, Circadian, and Prosocial Allocation Assessment

Detailed Description

This is a non-clinical observational behavioural study of adults aged 18 years or above. The study investigates whether naturally occurring differences in subjective sleep quality, sleep timing, and circadian preference are associated with prosocial decision-making in a computer-based allocation task.

Participants will first provide informed consent and will be assigned a participant code so that research data can be pseudonymised. They will complete demographic questions and sleep-related self-report measures. These measures include the Pittsburgh Sleep Quality Index, which assesses subjective sleep quality over the previous month, and the Munich Chronotype Questionnaire, which assesses sleep timing on workdays and free days and provides chronotype-related variables. Participants will also complete a 7-day sleep diary recording daily sleep-related information such as bedtime, estimated sleep onset, wake time, rise time, naps, subjective sleep quality, and schedule-related information.

Prosocial allocation behaviour will be assessed using a brief computer-based Dictator Game task. In this task, participants make hypothetical allocation choices involving distributions of money between themselves and another party. No deception cover story will be used. Participants will not be falsely told that they are interacting with a real paired participant if no real allocation exists. Dictator Game choices are hypothetical and do not affect actual compensation.

The primary aim is to examine associations between sleep quality, sleep timing, chronotype-related measures, and prosocial allocation behaviour. Secondary analyses may explore whether 7-day sleep diary measures provide additional information beyond retrospective questionnaire measures. Exploratory analyses may examine whether chronotype, sleep timing, or time of day moderates associations between sleep-related measures and Dictator Game behaviour. These analyses will be interpreted cautiously and will not be used to make clinical claims.

The study is not designed to diagnose, treat, or induce any sleep disorder, mental health condition, or other clinical condition. The PSQI, MCTQ, and sleep diary are used as non-diagnostic research measures. No clinical diagnosis, treatment recommendation, or personalised sleep advice will be provided. The expected risks are minimal and may include mild boredom or tiredness, mild discomfort when reflecting on sleep habits or making self-other allocation decisions, minor inconvenience from completing the 7-day diary, and privacy concerns about sleep schedule information. Risk will be minimised through informed consent, voluntary participation, the right to withdraw, non-clinical wording, pseudonymisation, separate storage of identifiable records, and restricted access to research data.

• Study Type: Observational
• Enrollment (Estimated): 128

Contacts and Locations

• Study Contact: Name: Cehao Yu, PhD; Phone Number: +852 3400 3012; Email: cehao.yu@polyu.edu.hk
• Study Contact Backup: Name: Junkai Che, Master; Phone Number: +852 9783 8643; Email: junkai.che@connect.polyu.hk

Study Locations

• Hong Kong
  • Kowloon
    • Hung Hom, Kowloon, Hong Kong
      • The Hong Kong Polytechnic University
      • Contact: Cehao Yu, PhD; Phone Number: +852 3400 3012; Email: cehao.yu@polyu.edu.hk
      • Contact: Junkai Che, Master; Phone Number: +852 9783 8643; Email: junkai.che@connect.polyu.hk
      • Sub-Investigator: Bryant HUI, PhD

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult; Older Adult
• Accepts Healthy Volunteers: Yes

• Sampling Method: Non-Probability Sample

Study Population

Adults aged 18 years or above will be recruited as healthy volunteers from university and community settings. Eligible participants may include university students, university staff, and community adults who can understand English or Chinese study materials and complete computer-based behavioural tasks, sleep-related questionnaires, and a 7-day sleep diary. The study is not limited to PolyU students and is not designed to recruit participants with any specific sleep disorder, mental health condition, or clinical diagnosis.

Description

Inclusion Criteria:

• Aged 18 years or above.
• Able to provide informed consent.
• Able to understand English or Chinese study materials.
• Able to complete computer-based behavioural tasks and self-report questionnaires.
• Willing to complete a 7-day sleep diary.

Exclusion Criteria:

• Aged under 18 years.
• Unable to provide informed consent.
• Unable to complete study materials in English or Chinese.
• Prior participation in the same study.
• Self-reported condition or circumstance that would make participation in a brief computer-based decision-making task or sleep-related questionnaires inappropriate or distressing.

Study Plan

How is the study designed?

Number of groups / cohorts

1

Cohorts and Interventions

Group / Cohort

Intervention / Treatment

Adult Participants; Adults aged 18 years or above who provide informed consent and complete sleep-related self-report measures, a 7-day sleep diary, and a computer-based prosocial allocation task. Participants are not assigned to any sleep manipulation, treatment, or intervention. Sleep quality, sleep timing, chronotype, and prosocial allocation behaviour are measured as naturally occurring individual differences.

Other: Sleep, Circadian, and Prosocial Allocation Assessment; Participants complete non-diagnostic sleep and circadian self-report measures, including the Pittsburgh Sleep Quality Index, the Munich Chronotype Questionnaire, and a 7-day sleep diary, followed by a brief computer-based Dictator Game allocation task. This is an observational assessment procedure only. Participants are not assigned to a treatment, sleep manipulation, sleep deprivation, sleep restriction, or behaviour-change intervention.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dictator Game Prosocial Allocation Score	Prosocial allocation behaviour will be measured using a brief computer-based Dictator Game task. The primary behavioural score will be the number or proportion of trials in which the participant selects the more prosocial allocation option across the task, with higher scores indicating more prosocial allocation choices.	Day 1 (single study session)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Pittsburgh Sleep Quality Index Global Score	Subjective sleep quality over the previous month will be assessed using the Pittsburgh Sleep Quality Index (PSQI). The PSQI global score is calculated according to standard scoring procedures and ranges from 0 to 21, with higher scores indicating poorer subjective sleep quality. The PSQI is used as a non-diagnostic research measure.	Day 1 (single study session)
Chronotype (Sleep-Corrected Mid-Sleep on Free Days, MSFsc) From the Munich Chronotype Questionnaire	Circadian preference (chronotype) will be assessed using the Munich Chronotype Questionnaire (MCTQ). The chronotype variable reported is the sleep-corrected mid-sleep time on free days (MSFsc), expressed as clock time in decimal hours, with later values indicating a later (more evening) chronotype. The MCTQ is used as a non-diagnostic research measure.	Day 1 (single study session)
Mean Sleep Duration From the 7-Day Sleep Diary	Nightly sleep duration will be recorded in a 7-day sleep diary and averaged across the diary days to yield mean sleep duration, reported in hours per night.	Daily for the 7 days before the study session (Days -7 to -1)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Dictator Game Response Time	Response time for Dictator Game allocation choices may be recorded as an exploratory behavioural measure, where available. Response time will not be interpreted as a clinical measure.	Day 1 (single study session)

Collaborators and Investigators

• Sponsor: The Hong Kong Polytechnic University

Publications and helpful links

General Publications

• Buysse DJ, Reynolds CF 3rd, Monk TH, Berman SR, Kupfer DJ. The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 1989 May;28(2):193-213. doi: 10.1016/0165-1781(89)90047-4.
• Carney CE, Buysse DJ, Ancoli-Israel S, Edinger JD, Krystal AD, Lichstein KL, Morin CM. The consensus sleep diary: standardizing prospective sleep self-monitoring. Sleep. 2012 Feb 1;35(2):287-302. doi: 10.5665/sleep.1642.
• Roenneberg T, Wirz-Justice A, Merrow M. Life between clocks: daily temporal patterns of human chronotypes. J Biol Rhythms. 2003 Feb;18(1):80-90. doi: 10.1177/0748730402239679.
• Brocklebank, S., Lewis, G. J., & Bates, T. C. (2011). Personality accounts for stable preferences and expectations across a range of simple games. Personality and Individual Differences, 51(8), 881-886. https://doi.org/10.1016/j.paid.2011.07.007
• Forsythe, R., Horowitz, J. L., Savin, N. E., & Sefton, M. (1994). Fairness in simple bargaining experiments. Games and Economic Behavior, 6(3), 347-369. https://doi.org/10.1006/game.1994.1021
• Ben Simon E, Vallat R, Rossi A, Walker MP. Sleep loss leads to the withdrawal of human helping across individuals, groups, and large-scale societies. PLoS Biol. 2022 Aug 23;20(8):e3001733. doi: 10.1371/journal.pbio.3001733. eCollection 2022 Aug.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): June 1, 2028
• Study Completion (Estimated): June 1, 2028

Study Registration Dates

• First Submitted: June 30, 2026
• First Submitted That Met QC Criteria: July 6, 2026
• First Posted (Actual): July 13, 2026

Study Record Updates

• Last Update Posted (Actual): July 13, 2026
• Last Update Submitted That Met QC Criteria: July 6, 2026
• Last Verified: June 1, 2026

More Information

Terms related to this study

• Keywords: Sleep Quality; Pittsburgh Sleep Quality Index; Chronotype; Prosocial Behavior; Sleep Diary; Circadian Timing; Munich Chronotype Questionnaire; Dictator Game; Prosocial Decision-Making; Allocation Decisions
• Additional Relevant MeSH Terms: Nervous System Diseases; Mental Disorders; Sleep Wake Disorders; Sleep Disorders, Intrinsic; Dyssomnias; Behavior; Social Behavior; Sleep Initiation and Maintenance Disorders; Altruism; Musculoskeletal and Neural Physiological Phenomena; Nervous System Physiological Phenomena; Sleep
• Other Study ID Numbers: HSEARS20260629007

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO
• IPD Plan Description: Individual participant data will not be shared outside the approved research team. Study findings will be reported in aggregate form only. Pseudonymised or anonymised data may be retained for future ethically approved research only if permitted by participant consent and institutional ethics approval.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No