Todd Anderson

The "2.3 hours lost since 1910" figure circulates widely online, but no sourced study confirms it, and the best available data points the other way. A systematic review of objectively measured sleep duration (polysomnography and actigraphy, 168 studies, 1960-2013) finds no significant decline over that period; a UK analysis using time diaries (1974-2015) actually finds a 43-minute average increase; and a comparison across 23 countries finds sleep duration stable or slightly rising in the large majority of cases, with a decline being the exception rather than the rule. The idea that "sleep isn't additive, it's an amplifier" of everything else (training, mood, patience) is a reasonable metaphor, consistent with what's otherwise known about how sleep loss affects cognition and mood — but it doesn't rest on any specific measurement in this post, and it doesn't need the wrong historical figure to stay valid. The shock statistic should be set aside; the general intuition (protecting your sleep matters more than you'd think) still stands without it.