1. In this prospective intervention study, both habitual and non-habitual nappers performed better on long-term memory tasks after an afternoon nap as compared to controls.
2. Habitual nappers demonstrated improved performance on both short and long-term memory tasks following an afternoon nap as compared to those who remained awake.
Evidence Rating Level: 2 (Good)
Positive sleep hygiene practices are associated with improvements in memory. However, frequent or habitual napping may result in difficulties in limited nocturnal sleep. Memory task performance may also be differentially impacted by napping in those who habitually nap versus those who normally remain awake during the daytime.
The objective of this prospective intervention study was to compare the impact of 90-minute naps on performance during memory tasks in habitual nappers as compared to non-habitual nappers. Adolescents aged 15 to 19 years were recruited and classified as habitual nappers if they recorded afternoon napping at least once per week. Participants were excluded if they had a history of sleep disorders, underlying illness, consumed 5+ caffeine beverages on a daily basis, or reported sleeping for less than 6 hours per night. Memory tests utilized included the Four Mountains task (4MT), a picture encoding task, and a factual knowledge test.
A total of 92 participants were included, with 46 participants in the napping group (25 habitual nappers; 21 non-habitual nappers) and 46 participants in the non-napping group (24 habitual nappers; 22 non-habitual nappers). Overall, napping was correlated with significantly increased performance on long-term memory tasks. Short-term memory tasks were only improved by napping in the habitual napping group. Limitations included small sample size, sleep duration over 24 hours was not reliably estimated, and age of onset of habitual napping was not collected. Nonetheless, the present study suggests that memory performance may be improved by napping, even in those who do not habitually nap.
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