There are reality checks you can do;

• Flip a light switch. If the lights come on you’re probably awake but if something else happens you’re dreaming.

• Try to push your hand thru a wall. In dreams you can do this.

• Read a piece of text, look away and re-read it. In dreams the text changes.

• Try jumping really high. If it’s a dream you’ll jump much higher than anticipated or even start flying.

Keep in mind though that these tests needs to be done regularly and in a serious manner even when you think you’re awake or else the habit wont carry into the dream world. Tell yourself; if my hand hits the wall I’m awake and if it goes thru I’m sleeping. Then do the test and see what happens. Be aware though that your brain is really good at explaining why weird things happen in your dreams. For example I once performed the jumping test and I just took off and went like “holy fuck I’m dreaming” but then I looked back and saw a crane hook attached to my back and went like ahh ofcourse makes perfect sense, nothing weird about that.

I also want to include a slight warning here. If you do realize you’re dreaming and aren’t immediately waken up by this realization then one thing that’s generally not recommended to do in dreams is look into mirror. The reflection wont be you or the very least it’s not what you expected and this might be really uncomfortable experience. Also; realizing that you’re dreaming may make you anxious and cause your dream to turn into nightmare. You can in theory turn this nightmare back into normal dream by for example hugging the monster but this is easier said than done.

Happy lucid dreaming!