Falling asleep is not a gradual process. It happens suddenly. In a new study, the brain activity of more than 1,000 people revealed a rapid transition between wakefulness and sleep, rather than a slow transition between the two states.
After all, our brain does not fall asleep gradually. Instead, it reaches a critical point where it quickly transitions from wakefulness to sleep. This is the conclusion of a new study in Nature Neuroscience.
Researchers have devised a new framework to study the brain’s behavior as we fall asleep, using electroencephalography (EEG) data.
This test, which records the electrical activity of the brain, indicates the stages of sleep and periods of wakefulness.
As detailed by , the team modeled 47 EEG signals in an abstract mathematical space, in which each data point had coordinates as if it were a point on a map. This allowed the team to plot brain activity during wakefulness and track it as it moved toward what they call the sleep onset zone, where brain activity corresponds to the second phase of non-rapid eye movement (NREM) sleep.
With this technique, we can now measure brain activity and, in every second, tell how close we are to falling asleep, to falling asleep, with unprecedented precision.
The approach was applied to more than 1000 people as they fell asleep, measuring the distance between brain activity and the onset of sleep.
On average, this distance remained practically unchanged until about 10 minutes before sleep and after dropped abruptly in the last few minutes.
To be critical point — which occurred, on average, 4.5 minutes before sleep — is the exact moment when the brain switches from wakefulness to sleep.
“These results suggest that the transition from wakefulness to sleep is not an incremental progression. It is an abrupt and drastic change that occurs in the last few minutes”, the leader of the investigation told New Scientist, Nir Grossmando Imperial College London.
This framework did not reveal the brain mechanisms that drive the transition to sleep. It may, however, help her to discover them in the future.
