Fifty healthy, young participants (10 male, 40 female) completed two 3-hour study sessions that were at least five days apart. The first session was a baseline. The sleep intervention took place on the night prior to Session 2, where the amount of time in bed was manipulated to be 60-130% of the individual's habitual sleep time. Within both sessions, subjective (Stanford Sleepiness Scale, SSS) and objective (Psychomotor Vigilance Test, PVT) alertness were measured. During the middle of each session, a 40-minute ad libitum meal opportunity allowed participants to eat from eight different food items. Food healthfulness, caloric density, distribution and number of calories were measured and compared to alertness levels.

Inclusion Criteria:

• Age: 18-45 years
• BMI: 20-29 kg/m²
• Eat breakfast at least 5 days per week
• Wake time occurs between 5&10AM at least 5 days per week
• Time in bed for sleep between 5&10 hours at least 5 days per week

Exclusion Criteria:

• Dietary restrictions that prohibit them from selecting one of the food choices offered in the study (e.g., gluten allergies, diabetes, vegan diet, dairy avoidance, allergies to the respective food choices available),
• are currently on a calorie-restricted diet, or
• are currently at a weight that is less than 20% of their highest weight within the last three years.
• Participation in shift work within 7 nights of the experiment
• Diagnosed as having severe sleep apnea syndrome, narcolepsy or chronic insomnia
• Diagnosed as having an eating disorder
• Active serious health condition
• Regularly taking vigilance-related medication (e.g., ADHD prescribed medication)
• Typically consume more than 600 mg of coffee or more than 10 cigarettes per day