Why do I always think about my problems right when I lie down to sleep?

Theres nothing else to focus on when you're just laying there! When we're busy we don't really have time to think about whats bothering us.

This is very normal because when we're about to sleep, it's the time where we don't have something to do or focus at. That's why our mind tends to wander off to different places, including the problems. Thinking about the problems it's fine, as long as you don't ruminate on it, leading to lack of sleep. If you find yourself thinking too much leading to lack of sleep, then bring your mind back to the current and now. Remind yourself it's time to sleep.

Problems coming up is the mind telling us that something is wrong and that needs to be healed. Sleep is a time when the brain processes information and emotions and also it's hard to get to sleep with everything out of order. You may need more time to wind-down, or you may need to do some introspection and see what areas you need to address inside of yourself so it's not hitting you all at once when you lie down to sleep.

I feel like I start to really think about my problems as I go to sleep because the simpler problems from the moment-to-moment of the regular day fade away, and I am left thinking solely about the bigger questions.

Because that is when you are not distracted, Your mind is empty of day to day things and so wanders to other problems, I know this can be annoying and mean you have a lack of sleep, but mindfulness can be very useful in this situation, check out the 7 cups guides for it

I believe it's because as you start the process of sleeping. You then beginning to think more, and you thinking can become clearly then during the day.

I feel that when you are laying in bed, that's when you look back at the whole day. Its best to try and think positively before sleeping.

You have racing thoughts. You may have drank caffeine early in the afternoon. If there is always something on your mind in bed, keep a notebook near your bed so you can write down things that come to your mind and you don't have to worry about them. Turn your electronics off. If you need more help send me a message. :)

I tend not to allow myself to fully process things as they happen, therefore everything comes up and out when my mind is beginning to quiet.

Maybe because you were really busy during the day and focused your attention somewhere else? When you lie down to sleep, you tend not to focus on anything and nothing catches your attention so naturally, your mind drifts to your problems. It's totally normal, by the way - don't worry about it! If it causes you trouble because you can't sleep, then perhaps you should try taking your mind off things by counting sheep or thinking positive thoughts.