When stock analysts lose an hour of sleep to Daylight Saving, they stop thinking for themselves and just follow the crowd.
SSRN · March 18, 2026 · 6432996
The Takeaway
It reveals that even professional market forecasters lose their independent judgment when tired, relying on the consensus rather than their own analysis. Conversely, gaining an hour of sleep in the fall makes them more independent, suggesting that market 'groupthink' is partially driven by sleep cycles.
From the abstract
Drawing on neuroscience and psychology, we study how sleep loss affects financial analysts’ herding behavior. Because sleep loss is empirically unobservable among analysts, we utilize the setting of daylight saving time change to identify when analysts are more likely to experience sleep loss. Using annual earnings forecasts from 2002–2020, we find that analyst herding—especially self-herding—increases on Mondays following the change to daylight saving time. The effect is stronger for analysts w