What could cause nightly itching on hands and feet, like from the inside out, under the skin?

A few things. Abnormal sensations in the hands and feet might indicate neuropathy, which often have an underlying medical cause such as diabetes, throid issues, arthritis and other issues. Talk to your doctor about this to see if this might be the case. You might see if regular skin lotion use helps. Dry skin can itch intensely! good luck.
Itchy hands and feet. Itching of the hands and feet is usually accompanied by a rash, often with very small blisters. The skin problem is called dyshidrosis and is easily treated with topical cortisone-like medications.

Related Questions

What is the remedy for the dry skin itching on hands, feet and legs?

Moistureizer. A skin moisturizer is very effective to relieve dry skin on hands, feet and legs. Try to get one that is fragrant free and uses coconut oil or lanolin so as to avoid harsh chemicals. Read more...