Online casino games offer the player the opportunity to play games that they normally could not easily play. If playing games online was out of the question, players would have to go out of their way to get to a land based casino. This means there is travel time and expense and dress code to worry about. Online play is less stressful in that there is no such thing as travel time and dress code. The player can use the time and money of traveling to play online while they relax in the comfort of their own home. Some players claim that they play several times a week for the relaxation, not for the money.
In principle I guess if you are playing for free then you can of course relax, then again if you are winning money it's going to be even more of a doddle. I enjoy playing my favorite Online Slot game Rainbow Riches for free. Players who play online can play whenever it is convenient for them however long or short the playing period is. A player who wakes up in the middle of the night can play online for a few hours to help pass the time. He may even relax enough to allow him to sleep.
Online play is also less stressful in that there is no casino staff interrupting the player's concentration. It is easier for the player to concentrate on his game when the background noise of the casino is absent. The player can concentrate better and make fewer mistakes while he relaxes in his own environment.
There is no scientific evidence that playing casinos online will relax you, however even if it helps take your mind off things that are distressing you.