A study-aid book says

> 
> may[might] as well - use when there is no reason no to do this.
> 
> 
> 

I have trouble understanding the difference between "may as well" and "might as well".

Do those two really mean the same?

Can they be replaced with each other, all the time?

For example:

> 
> I finished cleaning up my room earlier, so I **may as well** wash the dishes, too.
> 
> 
> 

> 
> I finished cleaning up my room earlier, so I **might as well** wash the dishes, too.
> 
> 
>