Email and attention: the actual cost of an interruption

Gloria Mark's 2008 paper at UC Irvine produced what has become the most-cited number in attention research: it takes approximately 23 minutes and 15 seconds to fully recover focus on a complex task after an interruption. The work continues for years after as researchers refine the figure, but the order of magnitude has held up (Mark et al., 2008).

Most knowledge workers in 2025 handle several hundred email and chat-tool interruptions per week. The math, if you take it seriously, is uncomfortable.

1. What "fully recover" means

The 23-minute figure refers to time required to return to the cognitive state one was in before the interruption — not just to start working again. People typically resume task activity within seconds. They reach prior depth of engagement substantially later.

The recovery includes:

• Reconstructing context (what was I doing?)
• Re-engaging working memory (which variables was I tracking?)
• Re-suppressing the now-active alternate task (the interrupting email)

For routine tasks, recovery is fast. For complex tasks — writing, analysis, problem-solving — recovery takes most of the 23 minutes.

2. The cumulative math

A worker who receives 30 interruptions per workday, each requiring ~23 minutes to fully recover from, has a problem. The 8-hour workday provides 480 minutes. Thirty 23-minute recoveries cost 690 minutes — more than the workday. The implication is that the worker is either (a) never operating at full focus, (b) batching interruptions to reduce their cumulative cost, or (c) doing work that doesn't actually require deep focus.

Most knowledge work falls into option (a). Workers who report feeling like they "got nothing done" despite working all day are often correct, in the sense that no single block of focus reached the depth required for complex output.

3. The interruption tax differs by task

Not all tasks pay the same interruption tax. Routine procedural work (data entry, simple email replies) recovers in seconds. Pattern-matching work (debugging, troubleshooting) recovers in a few minutes. Generative work (writing, designing, strategic thinking) takes 15-30 minutes to recover into.

The most valuable knowledge work pays the highest interruption tax. This is a structural feature, not a personal failure.

4. The intervention research

Studies have tested various interventions:

Batched email — checking email in 2-3 scheduled blocks rather than continuously — produces measurable improvements in mood, focus, and output. The largest study (Kushlev & Dunn, 2015) found 3x daily email checking produced higher daily wellbeing than continuous checking.

Notification suppression — turning off non-urgent notifications — reduces interruption frequency and improves task completion. Studies estimate 25-40% productivity gains in deep-work tasks (Mark et al., 2018).

Designated focus blocks — meeting-free, communication-free time blocked on calendars — reliably increase deep-work output when defended.

The interventions are widely understood. They are also widely not implemented, because most organizations have informal expectations of fast response that exceed what their formal policies require.

5. The honest summary

For an individual: interruptions cost more than they feel like they cost. The math suggests that complex knowledge work is essentially incompatible with continuous email/chat availability. Most successful deep workers have negotiated, formally or informally, blocks of uninterrupted time.

For organizations: response-time expectations should be made explicit, not implicit, and should account for the task complexity of the worker's role. A team where developers are expected to respond within 5 minutes is structurally incapable of producing complex output during work hours.

The cost is real. The implementation problem is mostly cultural, not technical.