At a time of night when most are sleeping, the experiments at the University La Statale in Milan, Italy, are just getting started. A team of neurophysiologists are investigating the mysteries of sleep. Asides from answering the fundamental question of why we need to sleep, their work could give key insights into the causes of sleep and sleep related disorders.
Marcello Massimini and his team of neurophysiologists have connected 63 electrodes to the head of a volunteer. As the night continues and the subject struggles against his sleepiness, electromagnetic signals are sent to his brain cortex to record his responses. The volunteer has a long night ahead of him; his brain responses are recorded and analysed until 5 am. He is then allowed to sleep for three hours before his brain receives further electromagnetic stimuli.
There is indeed a purpose to this process: Marcello Massimini is looking for variations in the neuronal interconnections of the brain. These interconnections are strengthened through learning. But since the brain has limited energy and space for these interconnections, sleep is required to allow the brain to eliminate those that are unimportant or not so useful. So says the theory that Massimini is investigating. The measurements taken should capture the state of the brain before and after the filtering process during sleep.
As part of the European research project “enough sleep”, Massimini's team will employ this same technique with people suffering from depression. It has been shown that depressive people feel better after a night of deprived sleep. Some scientists believe that depression is caused by a weakening in the strength of neuronal connection, primarily in the frontal lobe of the brain. Massimini would like to prove that the strength of the interconnections is improved when the depressed person doesn't sleep.
At the University of Claude Bernard in Lyon, France, a possible cause of hypersomnia has been identified: the histamine neuron. For years now these neurons have been the subject of study for Professor Lin. He has been comparing the behaviour between normal mice and mice that have been genetically altered to lack the histamine neuron. Professor Lin has discovered that a normal mouse, when placed into a new environment, will stay awake to explore the new surroundings. The mice without histamine in comparison fall asleep very quickly in the new environment. There are about 30,000 histamine neurons in the human brain and when they are not fully functional, we feel the need to sleep more. Such studies can therefore be useful in solving the problem of hypersomnia.
An act carried out by all animals, and amounting to one third of our lives, sleep is obviously something of great importance and necessity, as deemed by nature. Unlocking the secrets of sleep is no simple task. Much more research is required towards the understanding of the intricacies that work within the brain. But if possible treatments could be the result from this research, it would be a welcome relief to those many suffering from sleeping disorders.