Hi . Your fear may be due to some trauma or acute stress . People with. generalized anxiety also have this fear because they worry about everything.If you think you can't function properly you may consult a psychologist for assessment  and counseling.

Thats anxiety And it's treatable Kindly Consult for counseling

Statistically, we sleep approximately one-third of the time. So, right there, the odds are 2:1 that you will not die in your sleep. These odds are improved (?) by the fact that most of the things that might kill you can only happen when you’re awake and out about your day. Very few people have been run over by a bus while asleep in their bed. Maybe what worries you is that, from your point of view, sleeping seems like death? Nothing could be further from the truth. Our minds are busy, busy, busy when we’re asleep, and what they’re up to, though little understood, is apparently vitally important. Your sleep and your dreams are an important and all-involving part of your life. Much of what makes up your personality develops while you are sleeping. Far from being death-like, sleeping is an intensely creative, recuperative, and nurturing process during which you deliver profoundly needed maintenance to your body and soul. Learn to love your sleep and your dreams, Heather. In many ways, that’s when you’re most alive.

Hi, This situation, is related to some traumatic event or emotional situation. If you didn't have this problem before, it means something happened and there are some thoughts in your subconscious mind, so you need to consult with a psychologist/therapist to help you get rid of all these thoughts to have a better sleep. Do take care.

Thanatophobia is an intense fear of death or the dying process. While it's natural to feel anxious about death from time to time, thanatophobia is an anxiety disorder that can disrupt every aspect of your life. Take help from psychiatrist or psychologist about your fears

Hi

This fear could be due to overthinking about not getting sleep and how that might impact you the next day or physically. You can take a counselling session to better help you deal with the fear and anxiety

Hello dear I can understand what you might be feeling and going through. It might be hard for you to distract yourself from the thoughts of death and that scares you when you try to sleep. This might be affecting your health and productivity. Don't worry, consult a good therapist or a psychologist as soon as possible. You can also contact me and I will try to help you towards your recovery. Let's discuss your issues in detail so that you can get towards your recovery. Take care. Stay safe and strong. Everything will be alright. You got this!

Hi, there could be some past -ve experience or associated reasons related to your fear, kindly consult with mental health care professional he/she will do proper assessment and psychoanalysis and accordingly guide you how to get rid of negative thoughts and feelings. This fear of dieing during sleep is 100percent treatment within few sessions only.