14 DAY TRIAL // People who sleep heavily can consider themselves lucky. They generally get better rest than others, even in the most noisy conditions possible.
For example, these individuals can get a refreshing nap even if they fly in an airplane where countless small children decide to cry at the same time. They are equally “immune” to the sounds of car alarms, passing trains or aircrafts, and so on.
The new study was conducted by investigators at the Harvard Medical School, who published the results of their work in the August 9 issue of the esteemed scientific journal Current Biology.
According to the results, it would appear that the main advantage heavy sleepers have is a type of brain activity that essentially blocks out incoming noises, allowing these people to sleep through basically anything.
The new data were collected from electroencephalography (EEG) scans of 12 healthy test subjects.
During the experiments, the participants were subjected to a host of auditory stimuli, which were cranked up to the point where they disrupted their sleep patterns.
They were only allowed to sleep undisturbed for the first night, when researchers collected basal readings of each individual's sleeping patterns.
The following nights, the participants were placed in a bed towards which four massive speakers were oriented. During the sleep, they were bombarded with all types of noises, ranging from jet airliners taking off to conversations and music.
The researchers turned up the volume until the EEG readings showed disruptions in the test subjects' sleeping patterns. The anomalies, called “sleep spindles,” are in fact brief bursts of high-frequency neural waves, the team says.
“The volunteers would come in and we’d show them this luxury environment with a queen bed and comfy sheets, but there are these four very large speakers pointed straight at their heads,” explains Jeffrey Ellenbogen, an HMS expert and the coauthor of the investigation.
“If you know how many spindles a person is producing and compare them to others, you can predict who among them will run into trouble when it comes to blocking sound during sleep,” he adds.
“Although our computer […] uses ’sleep’ to refer to a process of temporary shut-down, that’s not the way our brain works. During sleep, our neurons are busy doing very complicated processing, including, this study shows, generating sleep spindles to protect us from being awoken from noises in the environment,” Elllenbogen tells Wired.
The new work adds additional credence to the idea that the human brain is in fact extremely busy during sleep hours, and not relaxing, as previously proposed. The HMS group is poised on continuing its investigations into this issue.