Supplemental materials Exam vs Lecture PeriodTable S1 shows the comparison of sleep parameters measured during lecture and exams period. Due to unequal sample sizes (with 58 students participating during lecture period, and 24 during exams period), 95% boostrap confidence intervals obtained with the percentile method with 10,000 replicates. Both t-tests and boostrap CI revealed only a significant difference for waketime.However, it can be seen that the 30 min shift (-.51 hours) in advance during the exam period was balanced by 20 min shift (-.35) in the bedtime. The time in bed differed of about 8.4 minutes

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Ambient light can influence sleep structure and timing. We explored how wearing an eye-mask to block light during overnight sleep impacts on memory and alertness, changes that could benefit everyday tasks like studying or driving. In Experiment 1, ninety-four 18–35-year-olds wore an eye-mask while they slept every night for a week and underwent a control condition in which light was not blocked for another week. Five habituation nights were followed by a cognitive battery on the sixth and seventh days. This revealed superior episodic encoding and an improvement on alertness when using the mask. In Experiment 2, thirty-five 18–35-year-olds used a wearable device to monitor sleep with and without the mask. This replicated the encoding benefit and showed that it was predicted by time spent in slow wave sleep. Our findings suggest that wearing an eye-mask during overnight sleep can improve episodic encoding and alertness the next day.

Ambient light can influence sleep structure and timing. We explored how wearing an eye-mask to block light during overnight sleep impacts on memory and alertness, changes that could benefit everyday tasks like studying or driving. In Experiment 1, ninety-four 18–35-year-olds wore an eye-mask while they slept every night for a week and underwent a control condition in which light was not blocked for another week. Five habituation nights were followed by a cognitive battery on the sixth and seventh days. This revealed superior episodic encoding and an improvement on alertness when using the mask. In Experiment 2, thirty-five 18–35-year-olds used a wearable device to monitor sleep with and without the mask. This replicated the encoding benefit and showed that it was predicted by time spent in slow wave sleep. Our findings suggest that wearing an eye-mask during overnight sleep can improve episodic encoding and alertness the next day.

Electroencephalography (EEG) studies of dreaming are an integral paradigm in the study of neurocognitive processes of human sleep and consciousness, but they are limited by the number of observations that can be collected per study. Dream studies also involve substantial methodological and conceptual variability which poses problems for the integration of results. To address these issues, we present the DREAM database—an expanding collection of standardized datasets on human sleep EEG combined with dream report data—with an initial release of 18 datasets, totaling 2331 data points. Each datum consists, at minimum, of sleep electroencephalography (≥20 s, ≥100 Hz, ≥2 electrodes) up to the time of waking and a standardized dream report classification of the subject’s reported sleep experience. This database will provide access to a larger pool of data than any single research group can collect and increase the statistical power of studies focusing on the neural correlates of dreaming. It will also provide useful criteria for methodological choices in future dream laboratory research projects.