Why does “one more thing” at the last minute derail my arrival time with ADHD
For many people with ADHD, getting out of the door on time is one of the most frustrating daily challenges. You might be ready to leave, coat on, keys in hand, and then notice one tiny task that suddenly feels urgent: replying to a message, loading the washing machine, or putting something away. Moments later, you realise you are running late again. This is not about poor discipline or lack of care. It is a well-recognised pattern linked to how ADHD affects time awareness, task-switching and executive function, the brain’s ability to plan, prioritise and control impulses. Understanding why this happens can help reduce guilt and build more effective, compassionate routines.
Why time slips away so easily
People with ADHD often arrive late or get thrown off by doing “just one more thing” before leaving because of how executive function differences affect time perception, task-switching and self-regulation. It is not about laziness or carelessness. According to NHS guidance on ADHD in adults, these challenges reflect genuine differences in how the brain plans, prioritises and manages transitions. Even small, last-minute actions can disrupt an already fragile time plan. When attention locks onto a task, disengaging requires significant mental effort, and the sense of urgency that usually signals “it’s time to go” doesn’t always register. People with ADHD also struggle with estimating how long tasks will take, a cognitive bias sometimes referred to as the “planning fallacy”. Because of this, a quick action like replying to a message or loading the dishwasher feels manageable but ends up taking much longer. These time distortions combine with difficulties switching focus, meaning that the smallest delay can derail punctuality. As Cleveland Clinic experts explain, this is linked to executive dysfunction and disrupted time awareness, not poor motivation or intent.
Executive function and time blindness
Executive functions are the brain’s control systems that manage planning, working memory and decision-making. In ADHD, these skills mature more slowly and often work less efficiently, making it harder to predict how long tasks will take or to shift from one task to another smoothly. “Time blindness” describes the sense that time feels abstract or slippery. People with ADHD may underestimate durations or only feel urgency when a deadline is immediate. Evidence from the Cleveland Clinic explains that this happens because the brain’s internal timing and dopamine reward systems do not track time consistently, leading people to act on what feels important “now” rather than what is scheduled next.
Task switching and the “one more thing” trap
Many people with ADHD find that transitions, such as moving from one activity to another, are particularly effortful. When the brain is engaged in something, like checking messages or tidying up, it resists shifting gears. Adding “one more thing” before leaving triggers micro-tasks and attention resets, creating a chain reaction of delay. ADHD specialists note that these challenges stem from executive dysfunction rather than poor motivation. It is a form of cognitive inertia; once the brain is in motion, stopping or redirecting takes significant effort. Tools such as countdown timers, alarms and visual cues help externalise time so that transitions become more visible and predictable.
What the brain studies show
Research using brain imaging has found that ADHD is associated with reduced activation in areas such as the prefrontal cortex and cerebellum during timing tasks. These regions help measure and anticipate time intervals. When their activity is inconsistent, people are more likely to misjudge how long tasks will take or lose awareness of time passing. Clinical reviews, including those cited by PubMed, describe these timing errors as measurable and not simply behavioural. They are influenced by attention variability, working memory limits and dopamine-based motivation systems, all part of the ADHD profile.
Guidance from NICE and NHS
The NICE NG87 guideline recommends psychoeducation, planning tools and behavioural supports to manage time and organisation. NHS resources further encourage the use of written schedules, visual reminders and step-by-step routines to reduce missed appointments or late arrivals. These strategies help externalise executive functions so that “mental time” becomes something you can see and act on. According to NICE and NHS recommendations, combining structure with flexibility gives people with ADHD the best chance of staying on track while avoiding last-minute chaos. Creating reliable systems such as preparing essentials the night before, using multiple reminders for different stages of getting ready and allowing realistic time buffers makes a significant difference. These approaches transform abstract time into concrete actions, helping to prevent that “one more thing” moment from taking control of your morning.
Takeaway
If you find that “one more thing” keeps making you late, it is not a personal flaw. It reflects how ADHD affects time awareness and transitions. With structured cues, visual tools and supportive routines, you can make time feel more tangible and manageable.
