Sleep and Food-based Decision Making

This study administers two prescribed sleep levels, each lasting one week, that participants will complete in their at-home environment. One week is a well-rested (8-9 hrs/night attempted sleep) and another is a sleep-restricted (5-6 hrs/night attempted sleep) condition. In between these two conditions is an ad lib sleep week. At the end of each treatment week, the participants come to a laboratory session to go through a series of decision making tasks. Participants also track dietary intake through the 3-week protocol using the ASA24 website.

This study was fully preregistered on the open science framework (OSF) has has registration DOI at https://doi.org/10.17605/OSF.IO/NSPRK

THE PRELIMINARY SCREENING SURVEY:

This short demographic, sleep, and mood survey is administered at least twice a year by the investigator (Dickinson) on random subsets of students at his institution. This database survey had been ongoing for several years and has been approved under separate human subjects approval process, and has been used by the investigator (Dickinson) to recruit for a variety of "sleep and decision" research studies over the years.

This short survey provides sufficient information for the investigators to screen out individuals who self-report a sleep disorder, who are not within the 18-40 year old target age range for this study, who are at significant risk of major depressive or anxiety disorder (assessed using validated short-instruments). Viable participants who meet the inclusion criterion (usually, only about 2/3 of those who complete the survey) are randomly assigned to either the control condition or a particular ordering of the treatment condition (SR-WR or WR-SR), ex ante. Afterwards, these individuals are invited to participate in the experiment via email. (note, participants are NOT allowed to opt into a condition or treatment ordering to which they were not randomly assigned)

THE SLEEP PROTOCOL:

The basic sleep protocol will involve recruitment of a total of 130 participants. Participants are randomly assigned to the control condition (N=30) or the treatment condition (n=100). The investigators anticipate some attrition such that n\>130 will be enrolled in the study to ultimately obtain n=130 participants who will have successfully completed the entire protocol.

Both conditions involve 3-weeks of at-home prescribed sleep levels for the participants. For the Control participants, week 1 prescribes 8-9 hours of attempted sleep per night for the 7 nights of that week (refer to this as a well-rested \[WR\] week). Week 3 for Control participants will be another prescribed WR week.

Treatment participants will be prescribed a WR week in week 1 or week 3 and a sleep-restricted (SR) week (5-6 hrs/night attempted sleep) then in week 3 or week 1. That is, treatment participants will be administered the treatment conditions either in SR-WR or in WR-SR order (counterbalanced across participants). For all participants (control and treatment), week 2 is an ad lib sleep week to wash out the treatment effects of week 1 before commencing the week 3 prescribed sleep level.

All participants will complete basic sleep diary records for the entire 3 weeks and will wear a validated sleep-tracking actigraphy device for the duration of the period. Objectively measured actigraphy sleep data will be scored using validated protocols.

The idea of the 3-week sleep protocol is to obtain within-participants measures of decision-making that will be assessed at the end of weeks 1 and 3 (the treatment weeks) with the participant in an experimentally manipulated state of well-restedness or chronic partial sleep restriction (similar to recommended WR levels and levels of SR common in many adult populations).

ADDITIONAL STUDY ELEMENTS In addition to decision making that will be assessed at the end of weeks 1 and 3 of the protocol (i.e., after each experimentally prescribed sleep week), participants will also complete daily food recalls of their dietary intake over the course of the 3-week protocol, as well as a short form of the International Physical Activity Questionnaire (IPAQ) and validated measures of cognitive and sleep function at the end of each week of the protocol. The IPAQ, as well as cognitive and sleep function assessments, will be administered online prior to the in-lab decision session at the end of each week (all three weeks). The daily food recalls will be completed online using the Automated Self-Administered 24-hour dietary assessment tool (ASA24).

Eligibility Criteria:
Inclusion Criteria:

* 18-40 years of age

Exclusion Criteria:

* at risk of major depressive or anxiety disorder (from validated screener), self-reported or suspected sleep disorder, extreme diurnal preference type (from validated screener)