The purpose of this study is to determine whether dexmedetomidine can be used to induce normal physiological sleep in humans.

Inclusion Criteria:

• Primary Inclusion Criteria for "Insomniac" subjects:

Subjects will be deemed "Insomniacs" if they suffer from any of the following:

1. Subject will be required to meet the criteria for insomnia, set by the International Classification of Sleep Disorders, which requires that a patient have difficulty initiating or maintaining sleep that is not accounted for by another sleep disorder, neurologic or psychiatric disorder or substance or medication.
2. Subject will be required to not be on any current pharmacological sleep disorder treatment.
3. Between the ages of 18 and 35 years.
4. Not taking any prescription medications that alter sleep, cognitive functions, or both.

Exclusion Criteria:

Primary Exclusion Criteria for "Healthy" control subjects:

1. Abnormal sleep habits:

   • sleeping less than 5 hours each night;
   • going to sleep before 9:00 PM or after 2:00 AM on a regular basis; or
   • Waking up before 5:00 AM or after 10:00 AM on a regular basis. This will be objectively assessed by wrist actigraphy measured for a 1-week duration prior to the first study night.

2. A sleep latency greater than 60 minutes, greater than 3 awakenings per night. This will also be objectively assessed by wrist actigraphy.

3. A score greater than or equal to 10 on the Epworth Sleepiness Scale.

4. Takes medication that alters sleep, cognitive function, or both.

5. Has a history of a known neurological or psychiatric problem.

6. Younger than 18 or older than 35 years of age.

7. Known or suspected sleep disorder(s).

Through completion of all three study visits (approximately 2 weeks).

Insomniac patients were not conducted as originally proposed due to difficult enrollment.

The Motor Sequence Task was not performed as originally proposed, so it has been removed as a secondary outcome measure.