Carlson's Law
Interrupted work takes significantly longer than uninterrupted work.
Tiny Summary
Carlson's Law states that work performed without interruption takes significantly less time than work performed with interruptions. Each context switch costs 3-15 minutes of recovery time.
The Cost
60-minute task:
Uninterrupted: [####################] = 60 min
5 Interruptions: [###]💬[###]💬[###]💬[###]💬[###] = 85 min
↑ 25 minutes lost!
The Science
Context Switch: 3-15 minutes per interruption
You lose: mental model, flow state (15+ min to regain), short-term memory, train of thought
Research: Average worker interrupted every 11 minutes, takes 23 minutes to regain focus → Never achieving deep work
The Formula
Effective Time = Work Time + (Interruptions × Context Switch Cost)
Example: 2-hour task, 8 interruptions, 5 min each
= 120 + (8 × 5) = 160 minutes
Efficiency: 75%
How to Protect Your Time
Block deep work: Calendar "Focus Block" 9am-12pm, phone on DND, Slack snoozed, decline meetings
Batch interruptions: Check Slack at 10am/2pm/4pm (not continuously), email twice daily, cluster meetings to afternoons
Signal availability: Headphones = DND, green status = available, calendar blocks = don't schedule over
Async-first: Default to written communication, document decisions, use threads not @here
Common Problems
Open office: Constant interruptions → Noise-canceling headphones, remote days
Always-on culture: Expected to respond immediately → Set expectations, batch responses
Meeting trap: Calendar fragmented into 30-min blocks → No-meeting days (Wed/Fri)
Key Insights
4 focused hours beats 8 fragmented hours. Makers need 2-4 hour uninterrupted blocks—a single 30-min meeting destroys a half-day. Managers can context switch but shouldn't impose their schedule on makers. Most "urgent" things aren't actually urgent—batch responses for 4+ hours of deep work daily.
Use the simulation to see how interruptions compound!