One thing I always do, every single night, is fall asleep to the sound of the Japanese language.
For me, and my learning so far, my sleep has been an important time of study and immersion. Now, I'm not sure if human beings actually learn during their sleep, however, I'm more interested in the time before and after you wake up.
Japanese is my alarm clock and my lullaby. I wake up to it on a morning and listen to it while I perform my chores, cook my morning nourishment, etc. and I close my eyes and rest my ears on the language until I nod off to sleep.
I'm not a neurologist, so I don't know why but there's something special about these two times of the day. Making it the first thing I heard on a morning and the last thing I heard at night has had a big impact on my Japanese. It's not just accomplishment bias, (as in, because I succeeded in doing it I, therefore, think it is correct), it was almost as if I could feel tangible improvement on some mornings and the only time I dreamt in Japanese during my first year was when I was sleeping with it playing it the background.
I went into the setup of my computer by pressing the DEL key when it boots up and instructed it to start at the same time every morning. I threw a playlist of my favourite shows in my startup folder and I, thus, set my Japanese alarm clock.
I kept up this habit from Day 1 and I've been big on repetition. I started by sleeping nightly to 秒速5センチメートル (5 centimeters per second) because it was exquisitely quiet.
I then migrated onto listening to ボイスドラマ (audio dramas) at night like AIR
Before finding my true love in ASMR. ASMR stands for Autonomous Sensory Meridian Response. It's growing in popularity on YouTube and the purpose is to relax the audience. The videos tend to include gentle whispering and relaxing sounds.
One of the main reasons why I even started this habit was because I just love listening to the sound of Japanese. It's even more pleasurable once you understand but I used to just listen to the sound of the language at first. With ASMR thrown into the mixture, sleeping has almost become a hobby for me.
For me, as well, this habit has helped me maintain my level when I couldn't push myself to actively learn some days. I'm a big believer in making the language that you're learning an integral part of your life, instead of just a timeslot in your day.
男(male)声(voice) / 女性(female gender)向け(orientated)
Lastly, if you plan to do this using a windows computer, you can tell your PC to automatically shut down by pressing the Windows Key to open up your start menu and type: shutdown -s -t XXXX.
Where X equals the number of seconds:
1800 = 30 minutes
3600 = 1 hour
7200 = 2 hours
Then press "Enter".