Seeing medical professionals. Check.

Trying to get enough sleep. Check.

Regular exercise?

Regular sleep timing (e.g. before 11pm everyday)?

Healthy diet?

Blackout curtains, noise insulation, and lower room temperature?

First can always try simple things. Drink a glass of warm milk (milk powder, fresh cow milk - get from indian seller - if they still exist) + raw honey (don't get supermarket honey) before sleeping. Raw honey can be from normal pasar. However having tasted those "malaysian raw honey" vs US raw honey, US raw honey tasted so much better.

Second, turn off all lights. Make environment really dark. Use eyepad if really necessary. Can get them from daiso.

Third, find a sound (white noise) your GF can relax. Just google on youtube and see which one she like. I recommend https://www.youtube.com/watch?v=OG2eGVt6v2o. Can be sound of waves, rain, waterfall, forest. Download the video, use VLC and continuous playback. Make sure the screen remains off so that it will still be dark.

Fourth, try meditation. It might be sensitive if you are not a Buddhist. However I have seen Christian people coming to learn meditation. Meditation is not purely for Buddhist. Is open for everyone like how yoga, exercise is. There are 2 types. I recommend metta meditation. Metta meditation is easier to do and easier to fall asleep. Speak with a proper Buddhist monk (not those Chinese temple monks)regarding a proper metta mediation.

Fifth, you can try certain supplements. Japanese matcha with the warm milk and honey is good choice. Matcha have been shown to relax oneself. Japanese monks drink matcha before meditation. Japanese matcha is not normal Japanese green tea. Is more expensive than normal Japanese green tea.
Melatonin - a hormone produced in the brain’s pineal gland) can help induce sleep. However cannot take long term or else effect will diminish.
Valerian Root - Valerian is well known for its sedative qualities and its ability to relax the central nervous system and the smooth muscle groups. It has been used as a sleeping aid for hundreds of years especially when there is excitation or difficulty in falling to sleep due to nervousness.
Rhodiola rosea - a adaptogen. Helps the body to deal with stress. Certain dosage will cause sleepniess. Certain dosage will cause a person to become energetic.
Chamomile tea - Chamomile has been used for centuries in teas as a mild, relaxing sleep aid
5-HTP - a precursor a tryptophan -  is a naturally occurring amino acid and chemical precursor as well as a metabolic intermediate in the biosynthesis of the neurotransmitters serotonin and melatonin from tryptophan. That's why drink warm milk cause it contain tryptophan.

Hope this helps.

Need to reevaluate the whole lifestyle to find the root cause.

Medication and supplements are not a long term solution.

I can chime in on this. I personally have this problem for many months. While it's easy to say that we don't have any stress/stressful problems in our life. A lot of these problems are not always obvious to us. For me, it's as simply as worrying about not be able to sleep.

Also, there's no 'normal' insomnia. Not being able to sleep is not normal. Lack of sleep will create a vicious cycle.

Lack of sleep > Stress (worried about not being able to sleep) > Anxiety (became worse) > Lack of sleep

Try to figure out what form of problems that she's going through in her life. If there's REALLY NONE. Then she need to seek specialized doctor. Try find doctors that are specialized in sleep.

Things that worked for me or I tried

1. Vitamin D3
2. Melatonin (though I double the dose and may or may not work sometime)
3. Avoid eating 2-3 hours before bed
4. Shower when it's time to sleep.
5. Dim all lights around her. Especially phones and monitors. If she REALLY need to look at those device. Download Twilight app for her phone and Flux for her computer.
6. Exercise. (Though this technically didn't work for me as I lift weights and weight lifting is a form of stress if rest is insufficient)
7. White noise, it depends from person to person. For me, any form of distraction is not good as I'll be focused on the distraction... wide awake
8. The best solution for me, alcohol. I happened to have a lot of whiskey at my disposal, so I tried. And it works wonder. Alcohol fogs your mind from all those troubling thoughts. I don't recommend downing a lot, I usually just pour a very small amount + ice and sips slowly.

Also, if her job is quite demanding or relatively busy, have her to take a few days off and go to a place where she can relax.

Sometimes you just need to reboot the biologic clock system. Force it to restart. Get a few days good sleep, the biologic clock should kick back in.

Try after work go for hiking (Gasing Hill/Wawasan) (if u work till 4-5pm)

If finish at 6pm.. Maybe can go nearby job ( heavy.. run of life)..

That how i disable the insomnia on me..

Seeing medical professionals. Check.

Trying to get enough sleep. Check.

Regular exercise?

Regular sleep timing (e.g. before 11pm everyday)?

Healthy diet?

Blackout curtains, noise insulation, and lower room temperature?

Something to clarify about myself, I work a rotating shift job. People kept saying stuff about biological clock and shit, but it's not really as simple as that. I sometime have this problem despite having a solid 2 weeks of business hours shift.

Now, my issue was a lot more severe back then. Out of an entire week, I might have 5 days with just 3-4 hours of sleep. It became worse when this goes on and on as I said, anxiety kicks in when you're always sleep deprived.

So you need to find out what works for her.

For me, if I work morning shift, I just take a shower when it's time to sleep. I take a melatonin if I have no sign of being sleepy before I take my shower. Usually if I don't fall asleep within 15 minutes, I'm bound to roll around for HOURS. So if I don't fall asleep within 30 minutes, I'll go out and pour myself a shot of whiskey. I'll wake up feeling thirsty but the side effect is better than NO SLEEP.

For night shift, I work from 10pm to 8am. I reach home at 830am. This is very tricky as there's a lot of light exposure causing your mind to be confused. Sometime I'm DEAD tired but I just can't bloody fall asleep. And I got myself very worried about this sleeping problems that I started sweating IN AN AIR CONDITIONED ROOM. So I did a lot of trial and errors and found out that I need to hit the bed as soon as I'm home. Any form of distractions (phone, computer ETC) WILL keep me awake. I hit the bed immediately and I'm usually asleep within 10-15 minutes. If all else fails, whiskey will fix it.

The issue is not totally gone from me as I had a lil bit of problem sleeping today morning after an entire night of working. I really like to lay on the bed and check my phone, so I ended up going for the whiskey route. Though, I woke up a few times within 7 hours of sleep. Quality of sleep is shit but better than no sleep.

I'm not asking your gf to become alcoholic, but alcohol works wonder in this situation. I think she's a bit similar to myself. My mind is very active and I kept thinking about various random things then I became frustrated that I can't fall asleep. Heart rate will elevate, then you started sweating making it near impossible to sleep.

But I did my research on alcohol. It's not really that bad if you just do a shot everyday. You can try finding her a bottle of red/white wine that she like. Red/white wine is actually good for your health if you take moderate amount everyday.

Sorry for the long write up.

I personally face anxiety, worried and unable to sleep. In the end I found out it's due to my weak emotion /mental strength.

For the remedy, I started to think and focus on problem positively. My body and mind managed to relax more which finally induce sleep.

Turning off smartphone and iPad does help.

Hope it helps.

Have you tried meditation yet? I find meditation helps alot to ease my stress which was causing some insomnia. Just the other night I woke up and was unable to sleep back, and I meditated 15 minutes and then managed to sleep soundly.

Most of the time the more we think to ourselves that we"need" the sleep and we keep telling ourselves to "Get to sleep!", the more we couldn't sleep. The key is to let go, just letting go will bring so much peace and I am able to have good sleep.

Piridone works for some people. It is very cheap. Not costly like xanax or other sleeping tablet.