Inclusion Criteria:  Age 18-64 Eligible to receive flu vaccination (at military hospital, DEERS eligible)  Exclusion Criteria:  Allergy or contraindication to getting flu vaccine Pregnancy or likelihood of getting pregnant in next few weeks Medical history of doctor diagnosed immune-compromising condition (HIV/AIDS, cancer, diabetes, significant cardiovascular disease) or doctor diagnosed sleep disorder (insomnia, narcolepsy).*Sleep apnea is an exclusion unless stable on treatment with cpap or oral device for more than3 months. Currently taking (or recently, in past 3 months) any immune suppressants or immunomodulating treatments (systemic corticosteroids, chemotherapy, etc) or sleep medication or supplement (including over the counter medications and melatonin)