What causes swollen/large veins in hand/wrists, mostly at night? b/p is good, but pulse is high. what would cause this in a 46 yo female?

Well hydrated : It sounds like high vascularity just meaning when you are well hydrated your veins expand out. Also some medications like vasodilators can cause this.

Fluid retention.: Hand veins can swell for many reasons but the most common is certainly hereditary . Other factors would be level of hydration, aging, sun exposure and loss of elasticity. Actually, I am amazed at the amount of women that i see with bulging hand veins. It is not uncommon to undergo some fluid retention while sleeping. This would make the vein enlarge.