Turns out our parents were right after all. Too much of anything is bad.
A new study published in the journal Sleep says that too much sleep is just as bad for your health as too little sleep. The study concludes that between seven and eight hours of sleep is the ideal range for optimal cognitive performance. The study’s results demonstrate that too much sleep correlates with similar cognitive deficits as those generally associated with too little sleep.
The researchers designed a set of twelve special tests to evaluate cognitive performance and developed an online portal where a thorough demographic questionnaire was put up. Participants were asked to complete the questionnaire along with the estimated sleep duration the previous night and take the twelve tests. Incomplete submissions were discarded and finally, the data of over 10,000 candidates was collected and analyzed.
Half of the candidates reported 6.3 hours or less of sleep at night. Interestingly, the results of the cognitive tests reflected a U shape. Candidates who slept less than the seven hours performed worse on the cognitive tests for reasoning and verbal abilities than the candidates who slept for the required number of hours (7-8 hours of sleep at night). Similarly, candidates who slept for more than 8 hours also performed worse than those who got the recommended 7-8 hours of sleep.
“We found that the optimum amount of sleep to keep your brain performing its best is seven to eight hours every night and that corresponds to what the doctors will tell you need to keep your body in tip-top shape, as well,”
Conor Wild, lead author on the study said.
“We also found that people that slept more than that amount were equally impaired as those who slept too little.”
Interestingly, it was found that oversleeping or undersleeping didn’t affect all kinds of cognitive performance. While reasoning and verbal abilities were affected quite a lot, short-term memory remained somewhat unaffected by short sleep duration, even going as low as four hours.
Thus, the study suggests that higher-order cognitive processes are most affected by bad sleeping habits. While previous studies have shown that complete sleep deprivation can adversely affect short and long-term memory, this study shows that these effects can be mitigated by sleep as little as four hours. More complex cognitive functions, such as problem-solving, however, require longer and more consistent sleep hours.
While more studies are required to ascertain why these effects are exhibited, this study at least corroborates the claim that 7-8 hours of sleep is ideal.