Hi Sarah, Welcome to HCM. You need not worry.Based on the information provided everything is normal with you. Firstly coming to the blue veins you noticed on saturday night, it could be due to the compression or pressure of had veins especially axillary vein. You might have slept on to the left side in such a posture that it compressed the axillary vein. When such a thing happens all the peripheral veins enlarge and due to the decreased blood supply your had tingling sensation of your hand. Once the pressure is relieved the hand returns back to normal. That is what might have happened to you on that night. Similar situation can also be encountered in people suffering from Thoracic outlet syndrome, but it often worsens with exercise. As you do not have any such complaints, you are unlikely to be having this. Coming to the more visibility of veins all over body- While sleeping as the gravity is eliminated while lying down and this makes veins more visible. As you get up due to the peripheral pooling of blood in veins due to gravity the veins tend to b less visible.Moreover you have mentioned that you have been running more frequently and longer distance. Because of this the venous drainage of the muscles increases during exercise and there by making them more visible. The veins even tend to show more prominently due to loss of sub cutaneous fat. Just stop worrying. You are absolutely normal and keep the good working going. A small advice is that try to avoid sleeping on one side through the night or putting more weight on one arm while sleeping. If the tingling sensation is severe, using preparations containing Vitamin B12 and antioxidants like Vitamin A, D, E and K will help you. Hope all your doubts are cleared. Wish you a healthy life and Take care