A Study to Evaluate the Safety, Tolerability, Pharmacokinetics (PK) and Pharmacodynamics (PD) of TAK-925 Study in Sleep-Deprived Healthy Adults

The drug being tested in this study is called TAK-925. This study will assess the safety,
tolerability, PK and PD of TAK-925 and will assess the effects of TAK-925 in sleep-deprived
healthy adult participants.

The study will enroll approximately 20 participants. Participants will be randomly assigned
(by chance, like flipping a coin) to one of the 4 treatment sequences—which will remain
undisclosed to the participant and study doctor during the study (unless there is an urgent
medical need):

- TAK-925 Low Dose + Placebo + TAK-925 High Dose + Modafinil

- TAK-925 High Dose + TAK-925 Low Dose + Modafinil + Placebo

- Modafinil+ TAK-925 High Dose + Placebo + TAK-925 Low Dose

- Placebo + Modafinil + TAK-925 Low Dose + TAK-925 High Dose

TAK-925 will be administered as an intravenous infusion based on the availability of safety,
tolerability and PK data from health Japanese participants in ongoing study TAK-925-1001.

This single center trial will be conducted in the United States. The overall time to
participate in this study is approximately 10 weeks. Participants will make a final visit 7
days after receiving their last dose of drug for a follow-up assessment.

Inclusion Criteria:

1. Be a nonsmoker who has not used tobacco- or nicotine-containing products (example,
nicotine patch) for at least 6 months before study drug administration of the initial
dose of study drug.

2. Have regular sleep-wake habits (example, routinely spending 6.5 to 8 hours sleeping
nightly, not oversleeping by more than 3 hours on weekends, that is, total sleep not
more than 11 hours) as determined by investigator interviews and confirmed in 5-day
actigraphy records and whom regularly fall asleep between 9:30 PM and 12:00 AM.

3. Be willing to have actigraphy monitoring during the week before randomization and in
each interval.

Exclusion Criteria:

1. Has a positive alcohol or drug screen.

2. Has a history of alcohol consumption exceeding 2 standard drinks per day on average (1
glass is approximately equivalent to: beer [354 milliliter per (mL/)12 ounces], wine
(118 mL/4 ounces), or distilled spirits (29.5 mL/1 ounce)] per day).

3. Has excessive sleepiness defined by a self-reported Epworth Sleepiness Scale score at
screening greater than 10; irregular work hours; or routine night-shift work within 1
month before randomization.

4. Currently experiencing or having a history of any known/suspected sleep disorder, any
disorder associated with excessive daytime somnolence (EDS), or any diagnosis
interfering with assessment of sleepiness.

5. Abnormal findings on the initial polysomnography (PSG) conducted on Day -1 (check-in),
as specified in the study manual.

6. Traveled across 2 or more time zones 2 weeks or less before screening.

7. Caffeine consumption of more than 400 milligram per day (mg/day) for 2 weeks before
screening (1 serving of coffee is approximately equivalent to 120 mg of caffeine).