Sleep is the largest variable you control
Short sleep degrades exactly what a timed reasoning paper taxes: sustained attention, working memory and speed.
What degrades first
Vigilance over minutes goes first, which shows up as careless errors late in a paper rather than an inability to solve items.
The self-assessment problem
People who are sleep-restricted consistently rate their own performance as near normal while measured performance keeps falling.
Before a test
A normal night beats a late revision session. There is nothing to revise for a reasoning paper, and the cost of tiredness is measurable.
Scored against age, education and area norms. Free certificate with a QR code anyone can verify.
Questions people ask
Does caffeine compensate?
It restores alertness partially and does not restore working memory to rested levels.
Best time of day to test?
Mid-morning suits most people; avoid the post-lunch dip and late night.