No more than any other day of the month.
Rest and relax just enough and still be active. Don't rest tun you into lethargic sloth? I am doling out lot of free advise? Aren't I?
A good night's sleep is always a good idea, especially during the menstrual period. Some people can maintain a very active lifestyle, but not everyone. It depends on health issues such as endometriosis and other possible conditions. If you struggle with fatigue or discomfort, discuss it with your doctor.
Average blood loss amounts to a few tablespoons of blood per day. Not enough to warrant curtailing activities. Having said that, hormone fluctuates warrants more rest during this time of the month.