Get a Shake and Wake…I have been using one for years…you have the option for strobe, sound or a vibrating disc that you put under your mattress. You can use all three settings and will be convinced the Martians have landed or just one or two settings. I use the vibrating disc under my 3 inch temperpedic mattress topper. Just make sure it is not directly under your head…just somewhere near your torso….it really vibrates. You will be jolted awake. The brand I have is Sonic Alert…Amazon has many types. I also have a small travel one that vibrates that I clip to a pillow.
The clocks numbers are large and mine has dimming options for the brightness and 2 different alarm settings. Also has a snooze function. Sonic Alert is my second one…first one lasted about 10 years.