Its impact on retraining your subconscious is tremendous.  Teeth in light contact + mouth taping is an effective combo.

also when you wake up if your palate isn't dry,is that good evidence that you were not mouth breathing in your sleep?

@kflps It could be, although it isn't uncommon for me to wake up with a dry mouth even though I tape it shut so it wouldn't be reliable to conclude your breathing habits during sleep based on that.

Regardless of your oral posture, taping your mouth shut still forces you to breathe through your nose which is good for several reasions.

I also have to say that my posture during the night greatly depends on how much I chew. When I do a lot of chewing my oral posture is on point  but when I become lazy with chewing my teeth tends to come apart during the night.

It wouldn't do any harm to do it anyways unless your are under the influence of some substanse that can cause respiratory depression

I started one week ago and I can already see that my subconscious is effected, in that I catch myself breathing through my nose more often than not through the day, even when I am doing heavy cardio! I also noticed...my skin is more clear.I am still tracking that. 

I've been taping since day 1. So for 7 months, really.

I believe it's one of the necessary factors amongst others like proper swallowing, nose breathing and posture and since I'm an adult, I felt like I needed to do everything recommended on the first attempt without realizing, "Oh, I should have done that", one day.

I've been waking up with my tongue on the mouth 90% of the time thanks to that. Well, the tip of the tongue tbh since I can't do the suction hold from the posterior third.

@azrael

I am actually not sure that the posterior third should be suctioned. Recently, I rewatched some of M. Mews videos. If I understood him correctly, he seemed to suggested that it is only the front and or middle that is being suctioned against the hard palate, whereas the posterior third is pushed up into the soft palate. This realisation really struck me, for several reasons. First of all, I was surprised I had managed to gloss over this sentiment, as I had watched the videos before. But most important of all, this may explain why most people don’t have any success with soft mewing, as this concept may be based on a misunderstanding of how one actually is supposed to mew(I.e only using suction), and further explain why many proponents of hard mewing has made progress(they incorporated pushing, the missing component of “soft mewing”) I am planing to make a separate post about this soon, but it seemed appropriate to vent this thought with you here. Btw, I have the same problem as you, namely only the tip of my tongue seems to be engaged while sleeping.

Regarding OP, I really do think taping is beneficial. It seems to have kept my mouth shut every time a I have tried it, and I am planning to start doing this every night soon.

I am new to correct tongue posture, mewing, etc. and I am not involved (yet) with appliance orthotropics.  I had extraction orthodontics. I have TMJ pain in the mornings due to clenching every night. 

Anyhow, I taped my mouth for the first time 4 days ago for 4 nights and I can't believe it.  I'd say the TMJ tension when I wake up is at least 25% less.  No dry mouth.  And deeper sleep.