Waking up exhausted every single morning despite 7-8 hours – what could I be missing?

For the past few weeks, I've been consistently getting 7-8 hours of sleep, tracking it, and avoiding screens before bed. Yet, I wake up feeling like I've barely slept at all and the brain fog lasts until noon. My doctor ran basic blood tests which came back normal. Has anyone experienced this and found a solution or a less common cause I should investigate?