REM sleep reduction effects on depression syndromes

In paper citation: (Vogel et al., 1975)

New conclusions:

1. N-REM sleep deprivation does not produce REM deprivation and REM rebound on recovery nights, but REM sleep deprivation does. (NREM sleep deprivation was acheived by waking participants up 10 minutes after they finished REM at the same rate as their REM-deprived partner)
2. In both endogenous and reactive depression, REM deprivation treatments caused REM deprivation, but only in the endogenous depressives did it also induce REM rebound on the recovery night.
3. Total sleep time was lower by about 40 minutes for everyone who received REM deprivation treatments  compared to controls.
4. EST did not reduce REM sleep the first two nights after treatment.
5. Endogenously depressed patients showed significant improvement with 3 weeks of REM sleep deprivation, but they did not have a significant difference in self-ratings of psychomotor activity (a symptom of depression)
6. 17 of 34 patients improved sufficiently for a hospital discharge after 7 weeks of increased REM pressure. Of these patients, 3 required rehospitalization within nine months of discharge, and 13 patients showed continued improvement.
7. 7 of 34 patients did not respond to sleep treatments or imipramine and received EST. Of these patients, 3  required rehospitalization within nine months of discharge, one went to a long-term care facility, and two showed consistent improvement. 
8. The unimproved patients were REM deprived, but did not show REM rebound. It may be that REM pressure is the force behind this healing process.

Other Important Information:

• Reactive depression is depression induced by a stimulus. Endogenous depression has a "spontaneous" onset.
• Tricyclics and monoamine oxidase inhibitors suppress REM sleep.
• EST has also been reported to decrease REM sleep. 
• If woken during REM, the patient was woken immediately at the onset of REM and kept awake for 3 minutes.
• If woken during NREM (controls) the patient was woken 10 minutes after the offset of REM so as to not disturb the normal REM sleep.

Remaining Questions:

• Is it REM deprivation, or increased REM pressure that relieves the depression?
• Is this method safe to use as a long term treatment?
• How could this treatment be made more efficient, affordable, and effective?