What Could Be Causing One To Feel Constantly Tired And Fall Asleep After Meals, And Is Their Low Blood Pressure A Concern?

Hi My husband is 60yrs old and lately he seems to be sleeping whenever he sits down or after a meal. It has been coming on for a while and I am quite concerned about him. Seems tired all the time these days. Checked his BP earlier and it was 119/52 with a pulse of 73. It is on the low side. Please advise what to do next. Thanking you.