Inclusion Criteria:

• * age: 50-75y old
• * BMI ≥25 and ≤45 kg/m2
• * a diagnosis of prediabetes AND/OR fasting glucose 100 mg/dL and/or HbA1c 5.7% OR Type 2 Diabetes diet-controlled and/or treated with metformin AND meeting 2 or more of the following metabolic syndrome criteria:
• * diagnosis of hypertension on stable medication regimen
• * blood pressure \>120/\>80 mmHg
• * A diagnosis of dyslipidemia on stable regimen
• * triglycerides 150 mg/dL
• * HDL cholesterol men \<40 mg/dL and women \<50 mg/dL
• * waist circumference men: \>102 cm (\>40 in); women \>88 cm (\>35 in)
• * in possession of a smart phone (iPhone or Android)
• * 70% of days with logging adherence (2 or more log entries/day separated by at least 5h)
• * Sleep duration 6-h, with habitual self-reported wake up time \>5AM and before 11 AM and average self reported bed time \<2AM
• * habitually eat breakfast
• * with weight stability within 5% of screening for the last 3 months
• * English speaking (the App has not yet been translated)
• * must live in the New York City metro area

Exclusion Criteria:

• * sleep disorder, e.g. known obstructive sleep apnea (OSA) on CPAP, severe OSA with apnea-hypopnea index \>30 events/h, significant daytime symptoms of OSA, periodic limb movements of sleep, narcolepsy, current shift work or in last 6-mo, travel more than 1 time zone during intervention; severe insomnia with score 15 on Insomnia Severity Index
• * significant organ system dysfunction/disease: severe pulmonary, kidney or cardiovascular disease; evidence of active illness (e.g., fever)
• * history of seizure disorder
• * previous bariatric surgery or on weight loss medication
• * history of or current significant food intake or psychiatric disorder
• * use of dietary supplements and/or medications known to affect sleep, circadian rhythms or metabolic function
• * smoking tobacco or using illegal or recreational drugs
• * consume excessive alcohol (women: \>14 drinks/wk; men: \>21 drinks/wk)
• * anemia (hemoglobin \<10 g/dl and hematocrit \<30%)
• * have conditions that render individual unable to complete all testing procedures \[e.g., unable to stay overnight or frequent travel across 1 time zones\]
• * extreme early and late chronotypes (\> 2AM bed time and wake up time before 5AM and \> 11AM)
• * severe food allergies
• * unwilling/unable to provide informed consent