At the annual meeting of the American Association for the Advancement of Science, researchers from the University of California, San Diego also presented findings on sleep efficiency across different age groups.
Boosting Memory
The researchers administered a simple memory test to a group of older adults with an average age of 68. Results showed that subjects who had more sleep time achieved higher test scores.
When the same memory test was administered to a group of young adults with an average age of 27, the results revealed that sleep quality, alongside sleep duration, is a crucial factor influencing memory performance.
AFP quoted Sean Drummond, the study's lead author and a professor in UC San Diego's Department of Psychiatry, on the 21st: "For young adults, sleep efficiency is important—they need longer periods of deep sleep."
"As we age, the most common sleep change is waking up around midnight, indicating lower sleep efficiency," he explained. "However, we found that midnight awakenings in older adults do not impair brain function or next-day performance. For young people, sleep disruption at midnight significantly negatively impacts brain function."
The Benefits of Napping
Another study by Drummond and colleagues examined the advantages of daytime naps.
"We first wanted to know if daytime naps provide the same benefits as a full night's sleep," said Sarah Mednick from the University of California San Diego's Department of Psychiatry. To test this, they conducted a series of tests beginning with visual learning tasks.
Results showed that if an adult could take a 90-minute daytime nap, they could achieve the same performance as after a full night's sleep.
Perhaps constrained by external conditions, many people cannot take afternoon naps and choose coffee to stay alert. Research indicates that a double espresso is less effective than a 20-minute nap.
"In some areas, like those involving perceptual memory, caffeine works as well as a nap," Mednick said. "But for tasks involving hippocampus activity—like memorizing vocabulary lists, phone numbers, or rosters—caffeine is less effective."
Habit "Contagion"
Regarding teenagers, researchers found that sleep disruption is consistently linked to marijuana use.
The National Sleep Foundation recommends that teenagers get 8.5 hours of sleep per night, while adults should aim for at least 7 hours.
A joint study by the University of California, San Diego, and Harvard University revealed that teenagers who sleep less than 7 hours daily are more likely to use marijuana and may "spread" their poor sleep habits and drug use to friends and siblings.
If one person in a group of teenagers sleeps less than 7 hours per night, the others are 11% more likely to be sleep-deprived and 19% more likely to use marijuana compared to peers who get adequate sleep.
This marks the first study to identify the "contagion" effect between sleep issues and cannabis use among minors. More alarmingly, the research indicates this contagion can spread up to four degrees—from one person to their friend's friend's friend's friend.