If you’re lying flat and typing on the laptop’s own keyboard, you’ll be reaching up, so yes, your arms can get tired.
That’s why most people who use a laptop lying down setup: the Flex-Stand holds the screen above you, and a wireless keyboard rests on your lap with the mouse beside you. Your elbows stay on the mattress and only your fingers move. Our Flex-Key keyboard and Flex-Click mouse are made for exactly this setup.
If you’re sitting up or reclined, lower the stand so the keyboard sits just above your lap, and you can type on the laptop normally.