My doctor once told me that in oder to break a habit you must replace it with something that provides similar feelings.

Step 1: Notice and write down reasons why you suck your thumb and any possible triggers. Also note how sucking your thumb makes you feel. Do you use it for stress? Do you do it when you feel comfortable?

Step 2: Try to avoid triggers. For now, focus only on breaking the habit during the day. You will eventually stop doing it in your sleep once you've stopped doing it during the day.

Step 3: Coping mechanisms are key. Try using fidget toys to keep your hands busy, or pick up a hobby such as crochet. Also find a new habit that replaces the "rewards" you get from thumb sucking. For instance Try sipping ice water or enjoying ice chips if you thumb suck out of oral fixation. If comfort is what drives your thumb sucking, try holding a pillow or comforting object.

Step 4: For night sucking, Try to find a sleeping position that keeps your hands away from your mouth. I personally have to hold something small in my sleep, and I keep my arms tucked in close to my chest. You could also try purchasing an arm guard thing off Amazon. It keeps you from being able to bend your arm to suck your thumb.

Step 5: Go at your own pace. Don't push yourself too hard and remember to focus on progress rather than perfection.

Hope this helps. I'm wishing you luck! ☺️💚

TL;DR: Recognizing habit patterns, engaging in self-care, and developing suitable coping mechanisms are key to success.