Sleeping long hours on the weekend makes you feel lethargic. Neuroscientists at Western University in Ontario, Canada, conducted this study and concluded that the optimal amount of sleep for logical thinking, concentration, and activity ranges between 7.16 and 7.38 hours.
Getting less than 7 hours of sleep negatively affected the participants’ performance in the test. Scientists also found that sleeping an additional two hours was linked to decreased cognitive performance and increased feelings of lethargy and inactivity.