How do i make something happen when the player wakes up

You can use a global variable so you can control when you want this event to be cancelled, this will also prevent the player from setting their spawnpoint on the bed, though you can still remove the variable check and add a new spawnpoint on x, y, z (as the event will provide you those coordinates from the block that was right clicked) + add the message rendered on the toolbar (And maybe adding an NBT tag / variable to stop it from activating when the spawnpoint was already set?) 

[player right clicks on block global procedure]

if globalvariable_a == true :
    if [provided block] == [bed] :

        if [is day] && [not][is thundering] :

            [cancel event]