Lack of Sleep Impacts Your Decision-Making

It is known that lack of sleep affects judgment and decision-making. This study tested two groups of volunteers. The first group got normal sleep and the other was deprived of sleep for 12 hours. After playing a standard gambling card game, it was noted that the sleep-deprived group had an inferior outcome in terms of advantageous draws and had lower understanding of rules. The authors conclude, “These results illustrate a role of sleep in optimizing decision-making, a benefit that may be brought about by changes in underlying emotional or cognitive processes.”

Studies have revealed that sleep deprivation can have severe effects on various psychological processes like decision making, mental functions on cognitive tests, tendency to undertake risks, and loss of behavioral inhibitions. On the other hand, restful sleep tends to allow for better learning capacities, deepens insight and creativity, sharpens memory, and helps acquire new skills. Restful sleep also allows for healthier moral judgments, reverence, and understanding of rules. This study attempted to compare two groups of people, with and without sleep deprivation, in terms of decision making, winnings, and understanding of rules in a standard card game.


  • Two groups of volunteers were selected. The sleep-deprived group consisted of 26 individuals while those with adequate sleep were 28 in number. There were two other control groups that performed the test in the morning (17 in number) and in the evening (21 in number).
  • The sleep-deprived group was subjected to a 12-hour lag without sleep before the experiment.
  • For the test, the “Iowa Gambling Task” was selected. It involved the presentation of four decks of cards from which each participant had to draw cards. Two of the decks were termed advantageous because they yielded fewer but certain rewards and more number of chances. The disadvantageous decks yielded high rewards, but also high and unpredictable losses.

Data/Results/Key findings

  • Compared to the sleep-deprived group, the group that had slept well performed better with draws that were more advantageous and better understanding of the rules of the game.
  • Both the morning and evening control volunteers did not show any difference in performance.
  • The evening control group did better than the sleep-deprived group. Conversely, the group that had slept well understood the rules better than the morning control group.

Next steps/shortcomings
The authors admit that getting more wins could be the result of the age, gender, personality traits, regular and uninterrupted sleep patterns, and reduced sleepiness during the test. These factors need further evaluation in this study. Future studies could have more decks of cards and more complex tests to facilitate a better understanding of the cognitive changes after sleep deprivation.

This study reveals that sleep deprivation puts a person at a disadvantage in tests like the Iowa Gambling test that involves understanding the rules and making precise decisions for more number of wins. Conversely, a good amount of restful sleep improves performance and understanding of rules. The study also included two morning and evening controls to rule out better or poorer performances at different times of the day. The results reveal that although the evening control group performed better than the sleep-deprived group, it was the well-rested group that understood the rules better than the sleep-deprived and control groups. This meant that sleep is essential to perform better at decision-making and cognitive tasks. The authors admit that this study supports the “adage that ‘sleeping on it’ is beneficial to decision making.”

For More Information:
Sleep-dependent Modulation of Affectively Guided Decision-making
Publication Journal: Journal of Sleep Research, 2011
By Edward F Pace-Schott, PhD; Genevieve Nave
From the Harvard Medical School, Boston, Massachusetts and Smith College, Northampton, Massachusetts

*FYI Living Lab Reports Are Summaries of the Original Research.

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