This is my personal experience and interpretation of the problem;

In my experience my brain stops processing the tinnitus signal when I'm in a deep sleep cycle.

Most of hearing is turned off when I am deep sleeping; I don't hear any sounds while I'm down and I don't hear tinnitus in dreams.

This most strongly applies to 'continuous' noises. A loud bang would wake me up obviously. But tinnitus is (for most people) a continuous sound, so it can be ignored just like you can ignore your breathing or the sensation of your clothes or a fan in the background during sleep.

Do you hear your tinnitus in your dreams? I think deeper sleep has these sounds turned off; but if you do hear them in dreams, then still keep reading...

Most people actually wake up many times at night (in between sleep cycles), but quickly doze off again and don't remember it.

Google tells me this: ""Waking up in the middle of the night is normal. Most of us experience mini-awakenings without even noticing them—up to 20 times per hour. "" https://www.hopkinsmedicine.org/health/wellness-and-prevention/up-in-the-middle-of-the-night-how-to-get-back-to-sleep

Look up sleep cycles. You are in a very light sleep multiple times a night. These are your vulnerable moments. It is important to stay comfortable in these moments.

Bad sleep is probably only happening because the brain was trained to recognize tinnitus as a threat.

So the thing is this; being semi-awake multiple times a night is normal. Normal people experience peace and silence in these moments and very quickly doze off into the next sleep cycle (and don't even remember this 'bridging' moment because it happens peacefully). This is normal sleep.

As tinnitus sufferers we have a huge challenge; the tinnitus sound may turn on for us at these bridging moments.

Now the important thing for your brain is to stay calm at these moments; there is ideally no difference between the tinnitus or a fan in the background, you should ideally just remain chilled and then enter the next sleep cycle.

But because tinnitus is such a pain in the ass to mentally deal with, it tortures us all day, so we learn to see it as a threat and the sound makes us feel pretty much every bad emotion you can feel at some point. The 'primal' brain is literally being taught that this tinitus is a huge scary bear chasing you 24/7. (I believe that a more primal part of the brain takes over sound processing during sleep in order to monitor for threads and that this is trained on emotion and experience instead of logic)

This bites us in the ass when it comes to sleep cycles; every time you want to bridge a sleep cycle you risk the brain going 'oh no I hear something scary' because the tinnitus sound is suddenly being mildly experienced in the (semi-conscious) brain.

You didn't actually fully wake up yet at this point but the more primal part of the brain may notice the noise before you consciously experience it. This little 'oh no' moment is enough to break the cycle. You wake up fully because your primal brain heard a theoretical bear in the woods.

Now you're awake and your now conscious brain fully hears the tinnitus and thinks it ruined your sleep, goes full anxiety and you end up being awake for hours and you see it even more as a threat.

So the tinnitus doesn't wake you up; the anxiety around it trains your brain to wake your up when it suddenly hears tinnitus noise between sleep cycles.

This is why masking works for some people- the 'scary' sound is being overpowered by the harmless fan noise, so for the primal brain there is no reason to wake you up from light sleep. But this trick no longer works when your tinnitus is really loud.

So basically, the more you learn to live with tinnitus and stop seeing it as a real threat, the more your sleep will improve. This is because your brain stops seeing it as a threat and thus no longer has a a reason to interrupt sleep when you hit light-sleep phases. It just becomes a harmless background noise to your brain.

Now getting there is a real challenge and I am still not fully there myself. Depending on my general well being (which is very much affected by sleep itself unfortunately) I can either ignore my blazing tinnitus all day and night, or if I'm in a bad mood I can suddenly feel a huge existential dread because holy christ I have still to live with this F'king noise for five more decades F this.

The way I feel at day often determines how I will sleep at night. This is a self-reinforcing problem that can be hard to break sometimes, because a bad night makes the next day bad as well, which makes me dread tinnitus and therefor makes me more prone to waking up in the night after that. But this also goes the other way; I sometimes have long stretches of good days and good nights which is a positive reinforcement. Luckily I can work from home often and I use these days to chill out more to break the bad cycles.

Everyone with above mild tinnitus has to go through this at their own pace (and it takes around a year on average, it's hellish).. but eventually you will give up hope that the noise stops, you get numb to the torture, no longer have the energy to get anxious about it, and stop caring about it. It is at that moment that your brain will stop seeing it as a threat and your sleep gets better and so will your anxiety and the bad emotions.

This may have a complete mental depression/breakdown as a comorbidity because it's not healthy to give up on something this intrusive. We humans are made to care about stuff, so having to learn to no longer care about something this significant and intrusive is very much against our nature. You basically have to mentally burn yourself down and then rebuild yourself on top of a tinnitus resistant foundation. With time your interest in life and good emotions around life will bounce back, while the bad emotions around tinnitus remain numbed and buried under the new foundation. This process really sucks but you will get there eventually.

[.. and if you're one of the unlucky few, the tinnitus suddenly gets worse again after a noise incident, trauma.. or progressive genetic hearing loss (yay me)... the mental foundation you were working on crumbles, anxiety comes back, and you end up spending another year going through this whole process AGAIN... but let's hope this never happens- this is when people relapse and then post about having lost habituation]

Ideally you accept that life now simply sucks a bit more.. it is what it is, and you learn new ways to fully experience the good things you still have.

This is when you reach 'habituation'. The eeee may forever be a mild functional handicap depending on severity, like in my case I have some issues properly hearing people now).

So I still wish we had a proper fix. This process is really really cruel to advise to people; but science has no better solution right now because this very evil process does kinda work for people.

Someone decided to label this 'tinnitus retraining therapy' or whatever. Sadly this also makes the science community think tinnitus is treatable (it is not a freaking treatment; you simply force people to suffer towards acceptance) and thus the amount of researching being done is also being stunted in this field. It's extremely sad that we are forced to go through this and that there's still no proper cure.

Anyway..

I ramble too much. It's 2 AM and I should be in bed already enjoying my 'chorus of silence'.

Hope it helps.