Serious fear of sleeping alone in the dark. i have to sleep with the light on when by myself. it's annoying what can i do? what condition is this?

Short Therapy: Your best bet is actually a very short course (usually 6 sessions) of cognitive behavioral therapy ... This has been proven time and again to work in these types of symptoms. You can ask your family physician if they have a doctoral-level psychologist in your area that they might recommend. Or, most psychiatrists will be happy to give you the name of someone. Hope that helps!

High anxiety: Fear of sleeping alone in the dark may reflect separation anxiety, most often seen in younger children. However, earlier fears and habits can persist into adulthood. Using a night light or keeping the light on is not a big deal if you don't disturb others. This fear may also reflect past trauma that you've "forgotten." A mental health professional can give you more guidance. I hope this helps.