When you are sleep deprived, is it possible to “catch up” by getting extra sleep?

A few nights of subpar sleep will leave anybody groggy, irritable, and a bit lacking in brain function. A major mechanism by which one becomes sleepy is the buildup of adenosine levels in the brain, which are lower after getting adequate sleep. Based on the adenosine hypothesis, sleep debt (caused by excessive adenosine levels in the brain) could be paid back at some time in the future by getting better sleep. However, recent animal studies suggest that this might not be the case. Instead, extended periods of sleep deprivation may lead to lasting brain injury through increased oxidative stress and inflammation that can worsen neurodegeneration.^[1] Although it remains to be seen whether similar mechanisms are at work in humans, 5–10 days of sleep deprivation impaired cognition in humans, which did not fully recover after 3 or more days of adequate sleep.^[2][3] This suggests that extended periods of sleep loss may cause lasting, negative effects on the brain that may not be “paid back” with a few days of good sleep.