Complex sentence: For this reason, it is not uncommon for hypomania to go unnoticed; often it is not until individuals are in a depressive episode that they seek treatment, and even then their history of hypomania may go undiagnosed.
Split into simpler sentences: For this reason, it is not uncommon for hypomania to go unnoticed. Often it is not until individuals are in a depressive episode that they seek treatment, and even then their history of hypomania may go undiagnosed.