The Interplay between sleep and wakefulness

DN Bureau

These two processes work in harmony to promote good consolidated sleep at night.

Representational Image
Representational Image


Washington D.C: Awake or asleep, we are basically under the regulation of two biological processes: sleep homeostasis, commonly known as 'sleep pressure', and the circadian rhythm, otherwise known as the 'body clock'.

These two processes work in harmony to promote good consolidated sleep at night.

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Researchers centered at the International Institute for Integrative Sleep Medicine at Japan's University of Tsukuba revealed some neuronal pathways, which regulate sleep/wakefulness states.

The ventrolateral preoptic nucleus (VLPO) in the brain plays a critical role in falling and staying asleep, while the lateral posterior part of the hypothalamus contains neurons (brain cells) that play a role in the maintenance of staying awake.

It also includes orexin neurons in the lateral hypothalamic area (LHA) and histaminergic neurons in the tuberomammillary nucleus (TMN).

Yuki Saito, who co-led the study said, "In our study, we aimed to identify the important players implicated in arousal regulation."

The team used recombinant rabies-virus-mediated trans-synaptic retrograde tracing in the mouse brain to analyze the architecture and function of hypothalamic circuits that link neuronal populations implicated in sleep/wakefulness regulation.

They found that these arousal-related neurons are heavily innervated by GABAergic neurons in the preoptic area, including the VLPO.

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The team further characterized GABAergic neurons in the VLPO that make direct synaptic contact with hypothalamic arousal-related neurons. hese two groups of neurons were overlapped each other, and both potently inhibited by the hormones noradrenaline and serotonin, showing typical electrophysiological characteristics of sleep-promoting neurons in the VLPO.

The full findings are present in The Journal of Neuroscience. (ANI)










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