Feeling rested is very subjective. If lying down without sleeping feels beneficial, then there isn’t necessarily harm. That’s unless wanting but being unable to sleep is making you frustrated and even more awake. Sleep experts suggest creating a strong association between bedroom and sleep, not bedroom and wakefulness. As soon as you feel any sense of frustration or perceived stress in bed, a negative association begins. Then, without being aware of it, your prolonged time in bed without sleep essentially trains your brain not to go to sleep in bed.
If that happens, you need to use sleep restriction to re-train your brain to sleep in bed. First, rather than lying there frustrated, do something else in another room, such as reading a book. Make sure you avoid blue light from tablets, computers, or cell phones. And intentionally cut down your time in bed, even if it means less sleep at first. Then add a little more time in bed each night, aiming for a percentage of at least 85%. In the process, you’ll make your body sleep longer and longer in bed, as you slowly build up your “sleep efficiency” (the time you spend in bed actually sleeping).