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.
Sleep inversion
Treatment of the delayed sleep phase type depends on the severity of the case. Mild cases may be addressed by an individual simply adhering to strict sleep and wake times. Severe cases may require incremental changes in sleep time, where a person sleeps 15 to 30 minutes earlier each day until an appropriate pattern is reached. Other methods of altering delayed sleep patterns include prescribing a night of sleep deprivation or the use of chronotherapy, a method in which sleep is delayed for three hours each night until the sleep pattern is rotated around the clock.