Insomnia
While insomnia is a common symptom of depression, antidepressants are effective for treating sleep problems whether or not they are associated with depression. While all antidepressants help regulate sleep, some antidepressants such as amitriptyline, doxepin, mirtazapine, and trazodone can have an immediate sedative effect, and are prescribed to treat insomnia. Amitriptyline and doxepin both have antihistaminergic, anticholinergic, and antiadrenergic properties, which contribute to both their therapeutic effects and side effect profiles, while mirtazapine's side effects are primarily antihistaminergic, and trazodone's side-effects are primarily antiadrenergic. Mirtazapine is known to decrease sleep latency (i.e., the time it takes to fall asleep), promoting sleep efficiency and increasing the total amount of sleeping time in people with both depression and insomnia.
Idiopathic hypersomnia
Currently, there is no cure for idiopathic hypersomnia. Also, because the underlying disease mechanism is not yet fully understood (see Causes), treatment efforts have usually focused on symptom management. Although there are several FDA-approved medications for use in narcolepsy, there are no FDA-approved medicines for idiopathic hypersomnia. Therefore, the wake-promoting medications used in narcolepsy are also commonly used off-label to help manage the excessive daytime sleepiness of idiopathic hypersomnia. "These treatments have not been studied to nearly the same extent in patients with idiopathic hypersomnia, and some patients with idiopathic hypersomnia do not achieve adequate control of symptoms with these medications."