Many researchers hold almost precisely the opposite opinion that sleep serves to re-activate synapses that were strengthened during the day, and thus reinforces their strength rather than diminishing it.
In her rearview mirror she could see the guy in the Range Rover glaring at her through his polarized sunglasses and switching his cell phone to the opposite hand so he could give her the finger, but she didn't dwell on his opinion of her for more than a moment.