Insomnia patients demonstrate subjective and physiological hyperarousal. The Cereve Sleep System has been proposed as a clinical treatment to reverse this hyperarousal in insomnia patients. The current study is a two dose study to determine the optimal temperature for the Cereve Sleep System. Primary outcome measures include EEG sleep measured sleep latency and sleep efficiency.

Inclusion Criteria:

Age >/= 22

Diagnosis of insomnia that meets criteria for DSM IV diagnosis of primary insomnia and International Classification of Sleep Disorders (ICSD)general insomnia criteria and RDC insomnia disorder criteria

Subjects must remain alcohol-free and avoid drugs that could affect sleep during the study.

>14 on the Insomnia Severity Index

Sleep -Wake diaries demonstrate sleep efficiency <85% on at least 50% of nights

Exclusion Criteria:

Neuropsychiatric disorders that may independently affect sleep, brain function or cognition, such as current major syndromal psychiatric disorders, including DSM-IV mood, anxiety, psychotic, and substance use disorders.

Specific exclusionary diagnoses include major depressive disorder, dysthymic disorder, bipolar disorder, panic disorder, obsessive compulsive disorder, generalized anxiety disorder, any psychotic disorder, and any current substance use disorder.

Unstable medical conditions Raynaud's Disease

Irregular sleep schedules including shift workers;

A latency to persistent sleep < 15 on either the sleep disorder screening night or the baseline PSG sleep night;

A sleep efficiency > 85% on either the sleep disorder screening night or the baseline PSG sleep night;

An AHI (apnea hypopnea index) > 10 and/or a periodic limb movement arousal index (PLMAI) > 15 from SN1

Body Mass Index >34

Use of medications known to affect sleep or wake function

Consumption of more than one alcoholic drink per day, or more than 7 drinks per week prior to study entry.

Caffeinated beverages > 4/day or the equivalent of more than 4 cups of coffee Unable to read or understand English