Brief Answer:
Medical treatment and sleep hygiene

Detailed Answer:
Hello,
Thanks for choosing health care magic for posting your query.

I have gone through your question in detail and I can understand what you are going through. Depression can occur with regular stress and it can also occur biologically without any stress as well. She needs proper treatment for the same. There are various effective therapies for depression like fluoxetine, venlafaxine, bupropion, mirtazapine or escitalopram and they are all very effective and mostly safe. She may also require some benzodiazepines like clonazepam or lorazepam for a short period like 2-3 weeks to reduce the anxiety and help with her sleep.

If she is averse to the drug therapies then there is also an option of cognitive behavioral therapy. This therapy is taken by either a psychologist or a psychiatrist in which the therapist identifies impaired cognition (Thoughts) and try to correct them. They are 15-20 min weekly session and there should be around 8-10 sessions to help her with her illness.

For sleep problems , she should firstly follow all the good steps of sleep hygiene.

1) Have some aerobic workouts during day preferably in the morning.
2) Have a light dinner.
3) Completely avoid coffee/tea/alcohol/energy drinks/coke/smoking.
4) Have a warm water bath before going to sleep.
5) Dont try very hard to go to sleep. If you are not sleepy then sit on a couch or sofa and do some reading and go to the bed only when you are sleepy.
6) Avoid watching TV or working on laptop/computer or bright screens at night.
7) Keep the lighting of your bedroom dim and make your bed every morning after you wake up so that you get a cozy bed to sleep at night.
8) Use your bedroom only for sleeping and resting and do not do any other work there.
9) Avoid afternoon nap for any reason.

Also it seems you have not tried the option of low dose quetiapine. You may take a low dose of quetiapine at 25mg or 50mg and this will give you a good sleep.

Hope I am able to answer your concerns.
If you have any further query, I would be glad to help you.
If not, you may close the discussion and if possible you may rate the answer for me, so that I get a good feedback.
In future if you wish to contact me directly, you can use the below mentioned link:
bit.ly/dr-srikanth-reddy

Wish you good health,
Kind regards
Dr. Srikanth Reddy M.D.

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