They often make psychotherapy more effective. Some patients feel guilty about achieving recovery with medication. They have been thoroughly indoctrinated in the idea that emotional disturbance must reflect psychic ills, and they expect the treatment to require a prolonged, painful search of their unconscious. What you're staying up for isn't worth it. The answer, in many cases, is both.
Many people find that as treatment progresses they return to normal sleep cycles.
This is healing in itself. If, after taking antidepressants for a while, you find your sleep has not returned to normal, it may be that the particular antidepressant you take has the unwanted side effect of insomnia. These antidepressants are not sleeping pills. Sleeping pills can be easily abused and are particularly dangerous for a depressed patient. Sedatives actually disrupt your normal sleep patterns and can quickly become addicting.