So taking the two together may cause insomnia, jitters, and a rapid heartbeat.

Long-term use of certain drugs commonly used during cancer treatment may cause insomnia.

Stopping or decreasing the use of certain drugs may also cause insomnia.

Phentermine should not be taken later in the day, as it can sometimes cause insomnia.

A product that may help most people sleep may cause insomnia in others.

You may need to be checked for other medical illnesses that may cause insomnia.

Or you may have another medical problem that causes insomnia.

For instance, a number of medical conditions, including heart disease and depression, can cause insomnia.

Drugs used to treat attention disorders can cause insomnia.

As one might expect, restless legs syndrome can cause insomnia.