According to new research from the UT Southwestern Medical Center, two proteins that link to alertness and sleep-wake balance were recently identified, which relates to a recent revelation that the quality of wakefulness affects the quickness in falling asleep in mammals.
“This study supports the idea that subjective sleepiness is influenced by the quality of experiences right before bedtime. Are you reluctantly awake or excited to be awake?” said Dr. Masashi Yanagisawa, professor of molecular genetics and a Howard Hughes Medical Institute investigator at UT Southwestern. He is principal author of this study, published online in May in the Proceedings of the National Academy of Sciences.
“Two of the great mysteries in neuroscience are why do we sleep and what is sleep’s function? Separating sleep need from wakefulness and identifying two different proteins involved in these steps represents a fundamental advance,” co-author Dr. Robert Greene, UT Southwestern professor of psychiatry and a physician at the Dallas VA Medical Center, said.
In this experiment, mice with virtually identical genes were separated into three groups. One acted as the control group, which slept during the day and were awake at night in a typical mouse pattern.The other two groups had 6 hours of sleep delay compared to the control group – but these two groups were kept awake in different ways. The one group had cage change events, where mice spent an hour exploring their new surroundings, while another group were kept awake as gently as possible by waving a hand in front of the cage or tapping them lightly whenever the mice were falling asleep.
As a result, both groups showed very different reactions: the cage-changing group took longer time to fall asleep than the gentle-handling group, even though their brain waves indicated equal amounts of sleep need or sleep homeostasis.
The researchers identified two proteins affecting these responses at different aspects of sleep: phosphorylated dynamin 1 levels were linked to how long it took to fall asleep, and phosphorylated N-myc downstream to the amount of sleep deprivation and corresponded to the well-known brain-wave measure of sleep need.
“The two situations are different biochemically, which is a novel finding,” Dr. Yanagisawa said. “These proteins are completely new to sleep research and have never before been linked to sleep need and wakefulness.”