Theoretical work is now in its final stages to try to predict when you will fall asleep.
In particular, the work of Dr John Kelly and his colleagues has focused on how our brain develops over time, based on a complex network of molecular interactions.
The results could change the way we think about sleep and wakefulness.
As well as identifying which parts of the brain are active when we are asleep, the new work has identified a number of key variables that determine how much of our waking brain is occupied with thinking about the future.
The research is published in the journal Scientific Reports.
“Our study is about understanding the brain’s capacity to process the vast array of stimuli in its environment, from a simple visual cue to a complex sensory experience,” Dr Kelly said.
“This process of processing is a key component of sleep and wakes.
We’ve found that the number of genes and proteins involved in this process is linked to the amount of time we spend awake.”
Sleep paralysis is a common problem in adults.
“When we’re asleep, our body goes into hibernation and the internal clock changes, and so we’re in a state of complete darkness for about 24 hours,” Dr Patrick McKeown, from the University of Queensland, said.
“This is when we wake up, which causes us to experience some waking, although we don’t realise it at the time.”
He said it was important to understand how the sleep cycle affected the body, how it changed over time and how to change it.
Sleep paralysis The first step to understanding how the brain works was to identify genes and protein pathways that encode sleep-related proteins.
This involved measuring gene expression in the brain.
Dr Kelly and colleagues identified genes that encode proteins that respond to visual cues that are related to the duration of sleep, or REM (rapid eye movement).
The genes are involved in the process of regulating our ability to process visual information, and this allows us to wake and go to sleep when we need to.
“These genes are the ones that are responsible for controlling our ability, and controlling the process by which our brain processes visual information,” Dr McKeon said.
The researchers found that sleep-specific genes are activated during REM sleep.
The genes also influence brain activity during REM, as well as during wakefulness, which is when our brains are most active.
This study identified the genes that are activated in REM sleep, and also how they are regulated during wake.
These genes are also linked to changes in brain activity over time.
The changes that occur during REM are associated with changes in sleep-wake cycle and circadian rhythms.
Sleep cycle and the sleep phase The next step was to determine how these genes change over time over the course of a night.
The team identified how genes in the sleep-reward pathway that were linked to sleep-time and wake-time were changed during REM.
These are known as the sleep and sleep phase genes.
They are linked to circadian rhythms, and they influence how much time we have to process and react to visual stimuli, such as the colours of the lights on the ceiling or the shapes of the curtains.
The gene changes are associated to the size of the hippocampus and prefrontal cortex, the regions involved in planning, and the ability to solve complex problems, Dr McKennow said.
This information led the team to identify a gene known as NPY (non-synaptic membrane potential), which is involved in synaptic plasticity, which means the brain can store new memories.
This gene is also linked with changes during wake, and changes in how we process visual input, and therefore, how much we have left to go to the toilet.
Dr McKennow said the findings could help explain why people fall asleep and wake up differently during different stages of sleep.
“The key is to understand that our brain is not like a computer or a smartphone that we can just go to and type out whatever we want,” Dr McDougall said.
A study by Dr McKenow and colleagues found that people with more NPY genes showed more sleep difficulties and sleep paralysis symptoms than people with less NPY gene.
Dr McDoughall said it could be a reason why people have more sleep problems and wake ups during their first few nights of sleep deprivation.
Sleep phase gene The next important step was determining which genes were involved in how the body develops the neural pathways that control sleep.
To do this, the team looked at a number different genes that regulate sleep and woke.
They found that a number are linked with different types of sleep stages, and that a gene called HSP60 (also known as gamma-aminobutyric acid), which has a role in the regulation of REM sleep stages and wake, was associated with the development of REM and REM-related brain regions in the hippocampus.
The hippocampus is involved with processing visual information and, consequently, is involved to a greater extent in sleep and waking.
“It’s the hippocampus that’s the main target for the sleep disruption process,” Dr Kjell Härle, from Lund