* Von Haller’s idea of sleep was similar to Aristotle, with his focus on the head being responsible for sleep, but instead of cooling, it was blood pressure * They were trying to focus on something more specific
* Piéron: first physiological perspective of sleep, thought that the substance would build up during the day and lead to sleep at night, that substance he called hypnotoxin * Hans Berger: discovered the EEG, very important because it showed that the brain had some sort of activity that could be recorded * Hard to record what is in the brains because of brain matter, bones, tissue etc. Another challenge is to make sense of what we are recording * Neural synchronicity: they have to activate in sync with other neurons, makes them more easily detectable and more powerful * Sleep spindles: kind of brainwaves, burst of lines when recorded, sign that the person is very much asleep * K complex: very high amplitude followed by very low amplitude, but the average amplitude is still higher than what you would usually find, gives us a good indication that the person is asleep * Kleitman: considered father of modern sleep research, thought that sleep was a very passive state * Observe a sleep deprived cats brain vs normal cat
* Neurochemical methods: see how sleep can be affected by drugs * MRI can help us see how the brain is activated while sleeping * The first measure that you need to study sleep is EEG, brain activity * The second is EMG, the electromyography or activation of the muscles (usually under the chin, easy to detect) * The last is EOG, or the movement of the eyes
* With these three basic measures, you will be able to identify quite a lot when it comes to sleep * But other measures can also be used: heart rate, reflexes, twitches, galvanic skin response, respiration, finger movement etc. * Different montages of electropde placements on the brain can be used with EEG to study brain activity (the way you install your electrodes will influence your results) * If both electrodes are placed at the same spot on both sides, there will be matching electric patterns, but if one is placed a little lower than the eye and the other is placed a little higher than the other eye, the patterns will be reversed a more exaggerated * Sleep recording: per 30 seconds of recording, you would have the equivalent of one page recorded on paper * With computers, we can now have paperless studies on sleep * Actigraph: watch type device that will record movement (if you move, it probably means that you are awake etc.) * Rechtschaffen + Kales: came up with a way of dividing the different sleep stages so that they can be studied more easily * Always a debate of whether stage one is sleep or awake and very relaxed (a person would not drop a pen they are holding at stage one, people can still maintain certain functions) * You will start seeing spindles, k complex or both at stage two of sleep, that is when you would drop the object * Awake and REM sleep waves are very similar (we need other measures to be able to differentiate them) * In stage one, the eyes start rolling in their sockets and rolling backwards...