Too much masturbation is bad for health, it doesnot cause much physical problem, but causes physical exhaustion. You will feel fatigue, headache, etc. Not using lube, will feel pain in the dick too. Once you masturbate, it takes 24 hours to fill the tank again. So dont go for more than once a day.
Reading your question it looks like you are a compulsive addict. That is a very usual phenomenon for a lot of guys who starts having a masturbation before sleep. When the body tunes to the system, you may lose sleep at night without that special weak feeling.
There are lot of people who are masturbation addict. Its not a good habit to be dependant on masturbation for sleep. Try to reduce and see if you can still sleep. I would suggest to limit within 2 to 3 times a week.