The investigators will conduct a randomized, controlled trial of internet-based cognitive behavioral therapy (iCBT) vs usual care for insomnia. The target population is patients prescribed medications for insomnia who have not had a dispensation of these medications in the preceding six months. The primary outcomes is dispensed days supply over the subsequent one year. Secondary outcomes include all types of health system clinical encounters. The investigators hypothesize that the group randomized into iCBT will have less insomnia medications dispensed than usual care controls, and less clinical encounters..

Inclusion Criteria:

• A prescription for any of a set of selected insomnia medications.
• Age >18 years at the time of the prescription.
• A recent (<30 days before the prescription date) diagnosis of insomnia as determined by a set of selected International Classification of Disease (ICD) codes, to be used for medications that are not prescribed just for insomnia.
• Membership for >365 days prior to the prescription date.
• No evidence of a dispensed insomnia medication within six months (183 days) of the current prescription.

Exclusion Criteria:

• Contained in inclusion criteria.