Sleep timing boosts study performance and shift‑work health in Brazil, Portugal

In Brazil, experts explain that there is no universally best hour for studying. Performance depends on individual factors such as a person's chronotype, age, sleep quality and the type of material being learned. André Rebelo, a high‑school coordinator at Colégio Vital Brazil, and psychologist Karen Scavacini of Instituto Vita Alere stress that the optimal study period is when a person is alert and has had sufficient sleep, not a fixed clock time. Morning sessions may help only if the sleeper is well‑rested; otherwise, discipline cannot compensate for sleep loss.

In Portugal, researchers highlight that working night shifts disrupts the natural day‑night rhythm, increasing the risk of cardiovascular disease, diabetes, certain cancers, mental‑health disorders and even dementia. Sleep deprivation impairs memory consolidation and emotional regulation. Scientists are investigating split‑sleep (biphasic) patterns as a possible mitigation strategy, but the consensus remains that the human body is biologically geared for daytime wakefulness and nighttime sleep.