This study will investigate the effect of two dietary patterns on sleep outcomes and measures of reported appetite. Participants will be given two different diets on two separate stays.

Normal sleep consists of alternating periods of non-rapid eye movement (NREM) and rapid eye movement (REM) sleep. The deeper stages of NREM sleep are also known as slow-wave sleep (SWS). Genetic and environmental factors, such as age, gender, race, socioeconomic status and others contribute to high inter-individual variability in sleep quality.

Current evidence from epidemiologic, clinical and experimental studies support a strong relationship between insufficient sleep and increased risk for obesity. A reciprocal connection between sleep and energy metabolism may exist between diet and sleep.

It is also well known that diet greatly influences body weight and metabolic health. Numerous disease risk factors are known to be associated with dietary patters consisting low fiber, high saturated fat, and added sugar, but the effects of diet on sleep quality remains unknown.

A small group of studies have indicated an effect of diet on sleep quality (assessed objectively by polysomnography [PSG]) under controlled laboratory conditions. However, none have experimentally tested sleep and appetite outcomes under different dietary patterns matched for macronutrients.

The overall objective of this study is to compare the effects of consumption of unhealthy meals with low fiber, high saturated fat, and high added sugar content i.e. simulated fast food diet [SFF] to healthy meals with high fiber, low saturated fat, and low added sugar content i.e. healthy diet. We hypothesize that a healthy diet (as recommended by the Dietary Guidelines Advisory Committee and the American Heart Association) compared to SFF diet will promote better sleep quality (as assessed by PSG) reflected by higher sleep efficiency, increased SWS and increased REM sleep and other improved sleep variables. We will also evaluate subjective appetite, mood and sleepiness as secondary outcomes.

Inclusion Criteria:

• Healthy male and female participants (age: 21-40 years and BMI=19.0-26.0 kg/m2) who habitually sleep on average 7-8 hours per night (as confirmed by actigraphy) and eat at least 3 meals per day (as confirmed by food diaries) will be studied. Subjects will be required to have stable sleep habits for the past 6 months and stable dietary habits for the past 3 months.

Exclusion Criteria:

• Obstructive sleep apnea by laboratory polysomnography or history of any other sleep disorder, night or rotating shift work (current or in the past 1 year), habitual daytime naps, recent (< 4 week) travel across time zones, extreme chronotypes, any acute or chronic medical condition, prediabetes or diabetes, prior or current eating or psychiatric disorders, claustrophobia, irregular menstrual periods, menopause, currently pregnant (screened with urine test), recently postpartum (within 1 year), currently lactating, alcohol abuse, excessive caffeine intake, smoking, illegal drug use, currently following a weight loss regimen or any other special diet or exercise programs, extreme food allergies or intolerances, and abnormal findings on screening blood testing. Participants will also be required not to take any prescription or over the counter medications, supplements that can affect sleep, metabolism, mood or appetite. Women will be required to not be on hormone replacement therapy.

Participants will undergo both diet pattern conditions but not be informed of their differences. The technologist scoring the sleep studies and actiwatches will be blinded to the condition