Aspects of the invention include methods of treating ADHD, anxiety or insomnia by applying a transdermal delivery device containing a dexmedetomidine composition formulated to deliver an amount of dexmedetomidine to a subject diagnosed as having ADHD, anxiety or insomnia. In practicing methods according to certain embodiments, a transdermal delivery device having a dexmedetomidine composition is applied to a subject and is maintained in contact with the subject in a manner sufficient to deliver an amount of dexmedetomidine sufficient to treat ADHD, anxiety or insomnia in the subject. Also provided are transdermal delivery devices configured to deliver an amount of dexmedetomidine sufficient for practicing the subject methods, as well as kits containing the transdermal delivery devices.
