A new study from the Wisconsin Sleep Cohort found that sleep inertia — the grogginess and impaired alertness experienced immediately after waking — is significantly associated with lower cognitive performance in older adults. Researchers assessed 461 adults averaging nearly 74 years old using the Sleep Inertia Questionnaire alongside standard sleepiness scales and six cognitive tests. Sleep inertia scores predicted worse performance on motor coordination (Grooved Pegboard) and executive function (Trail Making Test-Part B) even after adjusting for demographics, sleep quality, and psychosocial factors. Notably, general sleepiness measures like the Epworth Sleepiness Scale failed to show the same associations, suggesting sleep inertia is a uniquely informative symptom. The findings point to sleep inertia as a potential early marker of cognitive vulnerability in aging populations.
