Hate to say this, but, statistically, treatment for depression has precisely the same rate of recovery as getting NO treatment for depression.
Unless she is specifically manic-depressive, most depression treatments cause as many problems as they solve.
Some folks will simply pull out of it, and others will have great difficulty with depression their entire lives.
In my long experience with many family members and relationships with people so afflicted, there is really very little you can do or offer to make this any better.
You can suggest she go to 'therapy', but in my experience therapists are best at fostering dependency on therapy... I see very few people get "better' who would not have gotten better just talking to their friends, lovers, or priests.
the primary purpose I see in marriage counseling ( which my sister refers to as Marriage Canceling) is to get people to accept that its really over, unworkable, or doomed. This is mostly because counselors are, like any other vocation, mainly peopled with practitioners who are mediocre at their jobs.
While I believe a genuinely great counselor can teach a canary to live with a crocodile, I don't think that is likely to be the best destiny for either of them.
If she shows no signs of pulling out of this in a few months' time... chances are that she will be someone who struggles with depression her whole life long... and she may only grow to resent the fact that you do not. She may come to feel perpetually guilty because she so obviously is not giving you what you want in a relationship.. which is a source of guilt that only exacerbates her depression.
You have to assess for yourself whether you love her enough to ride this rollercoaster long term, or whether you need to find yourself a woman whose outlook and self image more closely match your own.
But first things first. The strongest real evidence thus far is that depression is not the cause of sleep disruption, but in fact the sleep disruption causes the depression. This may be due to circadian rhythms, and/or adequate exposure to sunlight. ( people in northern latitudes suffer higher rates of depression for no reason other than their lower exposure to sunlight )
Is she sleeping regular hours and up during the day when the sun is shining? Does she recall her moods as following a seasonal pattern? (i.e. depressed in autumn and winter, when cloud cover and shorter days reduce sun exposure )
Your best hope for her recovery is to discover that her depression is treatable by simply making sure she sleeps at night and is up during the day, or exposed to full spectrum light for at least 5 hours a day. ( buy higher wattage full spectrum lightbulbs for all your indoor lights )
Also... is she drinking? Alcoholics often suffer disrupted sleep... passing out early and waking at 2 AM unable to get back to sleep... and this causes a depression that reinforces the drinking.
In any event... I feel for you... depression in a loved one is one of the hardest challenges you can face. And dealing with it day in and day out can ruin the quality of your own life, without helping the person suffering depression in the slightest.
If it comes to saving yourself, rather than drowning together... then do so.
Even one less miserable person in the world is better than beating your skull against a brick wall.
