I've worked 4-10 hour shifts since I began with my company 7 years ago. This gave me Fri, Sat and Mon. off. They're now saying the business is changing and we'll need to work Mondays and we'll get another day off during the week, but it will be a random day based on how busy they are. I work nights and flipping from days to nights this many times each week will impact my sleep/eating patterns and I'm not eager to accept this change. Can I refuse? Would this be considered constructive dismissal? Thanks.