The answer to this question is a well-known one. All casinos are designed to keep players inside and spending money. This simply adds to the house edge. Casinos really don’t want you to know whether it is night or daytime.
Yes, there are no clocks in casinos. Imagine if you will, that you are playing at a casino and happen to notice the time on a casino clock. Well, in your mind you would say “time to call it a night.” This is the last thing a casino wants you to do. The longer you play the more money the casino makes.
One final note: You may think this is an illegal act, but in fact this policy is totally acceptable by the American Gambling Laws as well as other casino regulations worldwide.