As RVT said, it’s a business and companies want they’re trucks moving. However, reputable companies understand that drivers get sick on the road and are unable to drive. Thats part of their job is to problem solve these types of things. Only you…can determine if your unable to drive safely! Always remember, you are the operator of this rig. YOU are gonna be held accountable for anything that happens. If you don’t feel you can operate safely for ANY reason, (illness, personal, equipment, whatever) DONT!