The aim of this study is to learn how different doses of LY2624803 affect sleep in healthy Japanese participants. The study has four treatment periods. Participants will receive a single dose of LY2624803 or placebo in each treatment period.

Inclusion Criteria:

• Overtly healthy males or female Japanese
• Women of child-bearing potential, who test negative for pregnancy at the time of enrollment based on a urine pregnancy test and agree to use a reliable method of birth control during the study and for 3 months following the last dose of study drug
• Body mass index (BMI) of 17.6 to 26.4 kilogram per meter square (kg/m^2), inclusive
• Normal bedtime hours, with routine time spent in bed between 6.5 hours and 9 hours each night
• Clinical laboratory test results within normal reference range
• Venous access sufficient to allow blood sampling as per the protocol
• Are reliable and willing to make themselves available for the duration of the study and are willing and able to follow study procedures
• Have given written informed consent approved by Lilly and the ethical review board governing the site

Exclusion Criteria:

• Within 4 months of the initial dose of study drug, have received treatment with a drug that has not received regulatory approval for any indication
• Persons who have previously completed or withdrawn from this study or any other study investigating LY2624803 after receiving study drug
• Known allergies to LY2624803 or related compounds
• Women who are lactating
• Shift workers [those who shifted or plan to shift work within 7 days of any phase advance polysomnography (PSG) night] or any person who has crossed (or will have crossed) more than one time zone by aircraft within 3 days prior to entry
• Have an irregular or altered sleep/wake schedule that is likely to prevent from keeping a regular sleep/wake schedule during the study
• Regular napping (≥ 2 daytime naps/week by history)
• Extreme morning type or evening type
• Rhinitis, conjunctivitis, urticaria or chronic pain severe enough to interfere with sleep
• Nocturia that would interfere with sleep assessment
• Symptoms consistent with a sleep disorder or history of same
• Evidence of significant active neuropsychiatric disease and in particular evidence of significant medical or psychiatric illness within the past 12 months that could contribute to insomnia
• History or presence of cardiovascular, respiratory, hepatic, renal, gastrointestinal, endocrine, hematological, neurocardiogenic or neurological disorders capable of significantly altering the absorption, metabolism, or elimination of drugs; of constituting a risk when taking the study medication; or of interfering with the interpretation of data
• History or presence of orthostatic signs and symptoms within 2 years
• History of seizure or a close relative having a seizure disorder (such as epilepsy). History of a single febrile convulsion more than 10 years ago is acceptable. History of cranial trauma and loss of consciousness will be discussed prior to including any such participant
• Abnormal movements observed outside of normal sleep time
• Abnormal supine blood pressure and/or pulse rate
• Participants with orthostatic hypotension at screening
• An abnormality in the 12-lead electrocardiogram (ECG) that increases the risks associated with participating in the study
• Regular use of known drugs of abuse and/or positive findings on urinary drug screening
• Evidence of human immunodeficiency virus (HIV) and/or positive human HIV antibodies
• Evidence of hepatitis C and/or positive hepatitis C antibody
• Evidence of hepatitis B and/or positive hepatitis B surface antigen
• Evidence of syphilis infection and/or positive syphilis test
• Use or intended use of prescription (except oral contraceptives), over-the-counter or herbal medication, specifically antihistamines, anticholinergic medications or any medications that affect sleepiness, within 28 days prior to Period 1 dosing and/or during the study
• Participants who have donated more than 200 milliliters (mL) of blood or component blood within one month of screening, or those who have donated more than 400 mL of blood within 3 months of screening
• History of smoking within the previous 6 months of screening
• Participants who have an average weekly alcohol intake that exceeds 21 units per week (males) and 14 units per week (females), or participants unwilling to stop alcohol consumption for the period
• Participants whose daily caffeine intake does not permit maintenance of usual sleep/wake schedule
• No response to phase advance or a placebo responder
• Sleep disorders detected during the PSG screening night
• History or presence of breast cancer

All randomized participants.