YES ! you can chant mantra but you should not go to temple or should not do any religious pooja in home like idol worship decorating pooja rooms , even goddess too have menses ,in kerala some of the female god temple will be closed for certain period in month due to this, they say blood comes out of the sannidhi water outlets . so if god too has this then how careful and pure should should be humans . body gets tired and feel pain and fatigue . you cant concentrate on any things . thats why they restricted religious practices . but you can chant mantras within yourself sitting alone .dont engage in idol worship .