Does sleep inertia affect cognitive performance?
Yes — significantly. Reaction time, working memory, decision-making, and arithmetic accuracy are all measurably impaired during sleep inertia, sometimes equivalent to mild alcohol intoxication.
Documented impairments
Trotti (2017) reviews studies showing cognitive performance drops of 10–30% during the first 5–15 minutes after waking. Tasks involving attention, logical reasoning, and visual discrimination all suffer.
Comparable to alcohol
Some studies have shown the cognitive impairment during severe sleep inertia is comparable to a blood alcohol concentration of 0.08% (the legal limit for driving in many countries).
Practical implication
Important decisions should not be made in the first 15 minutes after waking. Daily routines should not include cognitively demanding tasks in that window unless they are designed to push through inertia (like ByeBed missions).
Sources
- Trotti, Nature and Science of Sleep, 2017. Sleep inertia: current insights
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