Why do I underestimate transition time when moving from one activity to departure with ADHD
Adults with ADHD often underestimate how long it takes to move from one activity to another because of measurable impairments in time perception, planning and time-based prospective memory. These cognitive challenges make it harder to judge the passage of time accurately, remember when to stop one task and start another, and prepare to leave on schedule. According to NICE guidance and NHS advice, structured routines, planning skills and external aids such as alarms, calendars and reminders are key to improving realistic time estimation, organisation and on-time behaviour.
Time perception and underestimating transition duration
A 2023 review of time perception in adult ADHD found consistent evidence that adults with ADHD struggle with time estimation and time reproduction. They often misjudge intervals, overestimate durations when reflecting on them, yet under-reproduce them when asked to measure time actively. This means that while they may feel time passing slowly in one moment, they still act as though they have more of it than they do. The result is chronic underestimation of how long preparation or transitions will take, leading to last-minute rushing or lateness.
Experimental studies confirm that these timing errors stem from irregular internal pacing and reduced time monitoring. When attention is absorbed in a task, adults with ADHD are less likely to check the clock, causing time to slip unnoticed until it is too late to transition calmly.
Time-based prospective memory and missed departures
A PLOS One study comparing adults with ADHD to controls found large impairments in planning and adhering to time-based intentions, such as remembering to act at a specific time. These deficits are less pronounced for event-based tasks, where an external trigger acts as a cue (“leave when the meeting ends”). This means clock-driven transitions, like “start getting ready at 7:45,” are especially vulnerable.
Virtual and naturalistic studies also show that people with ADHD make more timing errors in everyday tasks and rely heavily on environmental prompts. Without external reminders, they are more likely to become absorbed in the current activity and delay departure.
Executive function and the “planning fallacy”
Research links time-perception deficits with broader executive-function challenges in working memory, inhibition and cognitive flexibility. These are the mental processes that allow people to hold future steps in mind, stop ongoing actions and shift smoothly to the next goal. When they are impaired, transitions take longer than expected, yet the brain continues to underestimate the required time.
Cognitive models describe this as a form of “planning fallacy,” where people with ADHD assume transitions will take less time than they do. A tendency to focus on the present moment, combined with weak time monitoring, makes it difficult to visualise future stages of preparation accurately.
NICE and NHS guidance on improving time estimation
NICE NG87 highlights organisation, time management and prioritisation as key difficulties for adults with ADHD. It recommends psychoeducation and CBT-based approaches to build planning and time-awareness skills. The NHS Lothian Self Help Resource Pack advises using phone alarms to “remind me when to get ready and when to leave house,” checking calendars nightly and preparing items in advance. The East London NHS Foundation Trust’s Adult ADHD Support Resource Pack similarly recommends planners, routines and multiple alarms to structure daily transitions and improve punctuality.
CBT and coaching strategies for realistic timing
CBT and coaching programmes for adults with ADHD teach skills for realistic time estimation and planning. These include breaking tasks into smaller steps, scheduling buffer periods, and using staged reminders (for example, “start getting ready,” “ten-minute warning,” “leave now”). Trials of organisational-skills CBT show significant improvements in attention, daily structure and punctuality when participants learn to overestimate preparation time as a corrective strategy.
Practical takeaway
Underestimating transition time in ADHD reflects real, measurable differences in time perception and prospective memory rather than poor motivation. NICE and NHS guidance both recommend structured routines, behavioural planning strategies and external supports such as alarms, calendars and visual reminders to help. By adding buffer time, scheduling pre-departure cues and using multiple alerts, adults with ADHD can better anticipate how long transitions will take and arrive more consistently on time.
