Lack of sleep linked to poor and dangerous behavior; continuous and split sleep schedules affect cognition and glucose levels differently
Many adolescent students sleep less than the recommended duration of 8 to 10 hours a night. It is unclear; however, whether short night sleep combined with an afternoon nap is as good as having the same amount of sleep continuously during the night without a nap.
For the first time, researchers at Duke-NUS Medical School in Singapore have demonstrated that different sleep schedules with the same total sleep opportunity over 24 hours may have dissimilar effects on cognition and glucose levels. It is the first such study looking at the impact of sleeping schedule on brain function and glucose levels together, especially when total sleep is shorter than optimal. This is especially important since a lack of sleep has been linked to a risk for diabetes.
The study followed students aged 15 to 19 years for two weeks and they received either continuous sleep of 6.5 hours at night or split sleep (night sleep of 5 hours plus a 1.5-hour afternoon nap). The researchers found that under conditions of restricted sleep, students in the split sleep group exhibited better alertness, vigilance, working memory and mood than their counterparts who slept 6.5 hours continuously.
However, for glucose tolerance, the continuous schedule appeared to be better. The split sleep group demonstrated a greater increase in blood glucose levels to the standardised glucose load in both weeks.
This work was published in SLEEP. Although further studies are necessary to see if this finding translates to a higher risk of diabetes later in life, the current findings indicate that beyond sleep duration, different sleep schedules can affect different facets of health and function in directions that are not immediately clear.
Ideally, adolescents should be able to sleep 9 hours a night to minimise degrading their performance and mood, which many scientists have come to a consensus.
In another study by researchers at Flinders University in Adelaide, Australia, teenagers who slept less than peers were found more likely to take part in dangerous behaviours like smoking cigarettes, consuming alcohol and drugs, unprotected sex, driving dangerously on our roads and acts of violence.
Now, a new collaboration between Flinders University in Australia and Duke-NUS in Singapore will investigate a direct link between lack of sleep and poor emotional control which leads to dangerous behaviour amongst teenagers in Asia. The study will restrict the sleep of 58 adolescents in Singapore over multiple nights, measuring mood and rumination to evaluate the effect of sleep loss.
Many Southeast Asian students who move to Australia to study often face persistent sleep problems and there is a trend of decreased sleep in pursuit of academic achievement. These teenagers also have higher suicide risks which is linked to mood regulation and academic pressure.
If sleep loss results in more risky decisions, it can begin a self-perpetuating cycle with poor sleep leading to poor decision making about future sleep. Hence, the importance of sleep should be highlighted in future education campaigns because there is potential for simple interventions to have wide ranging benefits.
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