Does anyone else have 'time blindness' so bad they miss entire afternoons?

Yes. Severe time blindness is extremely common in adult ADHD, and what you’re describing is a classic presentation rather than an extreme one. Time blindness refers to difficulty sensing the passage of time internally. The ADHD brain tends to operate in a “now or not now” state, where future time is abstract and the present can stretch or collapse depending on engagement. When attention locks onto something, hours can pass without any internal signal that time is moving. Research shows impaired time perception as a core executive function issue in ADHD, not a motivation problem. Dopamine plays a key role in temporal awareness. When dopamine regulation is inefficient, the brain struggles to track duration, estimate time, and transition between tasks. This is why people often look up and realize half a day is gone, even without distractions like phones or social media. Adults with ADHD often compensate by over structuring or relying heavily on external cues such as calendars, alarms, or deadlines. Without those anchors, time can disappear entirely. This is also why afternoons are a common “black hole,” especially if the morning required intense effort or masking. Importantly, this is not about being careless or lazy. It reflects a neurobiological difference in how time is experienced. Treatment that improves executive function, including medication and external time supports, usually reduces this significantly, but most adults still need visible time cues to stay oriented.