Perception of sleep quality can have a significant impact on cognitive performance, as demonstrated by a study where participants were manipulated into believing they had either slept 5 or 8 hours. Those who believed they had slept 8 hours, even if they had only slept 5, showed no decrease in cognitive performance. However, those who believed they had only slept 5 hours experienced a decrease. This highlights the importance of understanding the placebo effect and the potential negative impact of poor data from sleep trackers.
