The goal of this randomized crossover clinical trial is to determine if habitual sleeping habits can predict endurance performance following a night of partial sleep deprivation in healthy untrained, recreationally trained, and trained cyclists (18-50 years, ~50% females). The main questions it aims to answer are:

1. Can habitual sleeping habits predict, or do different types of sleepers alter, performance outcomes following sleep deprivation?

2. Does sleep deprivation alter blood pressure, heart rate, or metabolic responses during a 20-minute time trial, and/or are these altered amongst different types of sleepers?

   • Participants will be asked to perform 4 performance tests (20-minute time trial), 2 for familiarization, and 2 testing visits (1 under normal sleep and 1 under partial sleep deprivation).
   • For 1 week prior to each testing visit, sleep will be tracked using an ActiGraph device.

The investigators hypothesize that habitual early sleepers, poor sleepers, those with greater variability in sleep duration, and females will show the greatest impairments in performance following partial sleep deprivation.

Five separate visits will take place. Participants will be asked to abstain from heavy exercise, napping, alcohol, recreational drugs, and acute supplementation or medication use (i.e., melatonin, antihistamines) 24 hours before each visit. The first visit will always be the introductory visit, which will be followed by two familiarization visits. The next two visits will be testing visits and randomized (one normal sleep visit and one sleep deprivation visit).

Introductory visit: Prior to arriving at the lab, participants will read over and sign the consent form, complete the Pittsburgh Sleep Quality Index (PSQI), complete the Morningness-Eveningness Questionnaire (MEQ), complete a general health questionnaire, and complete the PAR-Q+ remotely. After obtaining consent and upon arriving at the lab, height and weight will be measured. This will be followed by a maximal exercise test to assess peak oxygen uptake (VO2peak) on a cycle ergometer. After this, participants will be given a rest period, which will be followed by the completion of a 5-minute time trial so the participant can get familiarized with pushing themselves during the performance test.

Pre-testing: Participants will be equipped with an ActiGraph device to measure sleeping patterns over a 1-week time frame prior to each testing visit as well as the night prior to each familiarization visit. These data will then be used to determine each participant's sleep-wake schedule for the testing visits. Furthermore, the day prior to each familiarization visit and testing visit, participants will be asked to complete a food diary using an online app (MyFitnessPal), which will ask participants to list the ingredients and quantity of each ingredient consumed for each meal and beverage that day, night and subsequent day. Participants will be asked to abstain from food for 4 hours upon arriving at the lab, prior to each familiarization and testing visit.

Familiarization visits: Upon lab arrival, participants will be provided with a standardized snack, which includes instant Quaker oats mixed with water. The amount will be based on body weight (1 gram of carbohydrates per body weight in kilograms). Following this, the participant will complete a 20-minute time trial on a cycle ergometer.

Testing visits: Upon lab arrival, participants will lay supine quietly, and resting hemodynamic measurements (blood pressure and heart rate) will commence. Following this, participants will consume the same standardized snack as the familiarization visit, and then a 20-minute time trial on a cycle ergometer.

Inclusion Criteria:

• Ages 18-50 years
• Free of known cardiovascular or metabolic diseases or sleep disorders
• No history of smoking (within the past 3 months)
• Able to engage in physical activity assessed through the physical activity readiness questionnaire (PAR-Q+) (answer no to all questions
• No prescription of chronic medications other than oral contraceptives
• Able to abide by sleep protocols for all visits
• Individuals who are able to consume the ingredients of instant oatmeal (whole grain oats, sugar, salt, and natural flavour)
• Individuals who are not pregnant

Exclusion Criteria:

• Ages <18 years, >50
• Individuals diagnosed with cardiovascular or metabolic disease or sleep disorders
• Has a history of smoking (within the past 3 months)
• Not ready to engage in physical activity (answer yes to one or more questions in PAR-Q+)
• Individuals with prescription of chronic medications other than oral contraceptives
• Unable to abide by sleep protocols for any testing visit
• Individuals who are unable to consume the ingredients of instant oatmeal (whole grain oats, sugar, salt, and natural flavour)
• Pregnancy

Participants and investigators are blinded to power output during the time trial