Sleep and Dreaming in Humans

the purpose of this experiment is to study the nature of sleep although many people think of sleep as a very quiet state a state in which the mind and the brain are turned off the truth is very far from this sleep is actually a composite of many different states and the sleeping subject is continually shifting from one state to another throughout the night the shifting between stages does not occur at random however there is an orderly sequence of changes that repeats itself approximately every 90 minutes throughout the entire night the stages of sleep are defined by the physiological activity with which they are associated however some physiological measurements are more important than others in sleep research important measurements are the electroencephalogram or brain wave activity the electro oculogram or eye movement activity and the electromyogram or muscle activity these activities are measured by means of small electrodes which are attached to various portions of the skin i will now demonstrate this simple technique by attaching one of the eye movement electrodes to the subject the electrode is a small disc and the cup is filled with electro jelly before attaching this electro jelly facilitates the conduction of electrical currents between the skin and the electrode itself in this particular case i will attach the right outer canthus electrode the electrode is placed as close to the eye as possible without actually covering the eyeball and the small plastic tape around the electrode is pressed as tightly as possible so as to ensure an airtight compartment which will prevent drying of the electrode jelly the complete array of electrodes has now been attached and there are 12 in all there are four electrodes placed around the eyes these two record horizontal line movements the right outer campus and the left outer campus these two record vertical eye movements the supra orbital electrode and the infraorbital electrode there's no need to have electrodes uh around the right eye because both eyes move in synchrony there are two electrodes here which record the electromyogram from the digastric muscles and the array of electrodes for the electroencephalogram is frontal central and occipital these two are attached by means of collodion or cotton pads soaked in clothing which are placed over the electrodes and the frontal electrode is simply attached right below the hairline with elastoplast tape the electrode in the center of the forehead is the ground there are also electrodes on the right and left earlobes which are used as references standard references for recording monopolar eg patterns the subject is now prepared for an all-night sleep recording the jacks on the lead wires are plugged into the terminal box which in turn is connected to the polygraph each jack is plugged into a specific number so the experimenter will be able to select any pair of electrodes he wishes to record from the length of the cable that is formed by the lead wires is sufficient to allow the subject a complete uh freedom of movement in bed he can roll over he can sit up if necessary and the fact that the criminal box is behind him usually prevents any entanglement with the cable the electrodes from the subject lead to the terminal box to this eight channel type r dyna the subject is now awake and each channel is recording a different electrophysiological parameter channel 1 is recording monopolar eeg activity channels 2 and 3 are recording monopolar horizontal eye movements channel 4 is recording bipolar vertical eye movements channel 5 is recording spontaneous skin potential or electrodermal activity fingerprismographic activity is being recorded on channel 6. the cardiotachometer is measuring changes in heart rate on channel seven emg activity is being recorded on channel eight i will now have the subject move his eyes in the horizontal and vertical planes steve will you move your eyes left right left right now look straight ahead now up down up down the variables that we will record throughout the entire night without interruption will enable us to have an ongoing definition of the sleep stages these stages recur in a consistent fashion throughout the entire night and the way in which they recur is very consistent from subject to subject on the argument of this graph we have the eeg stages of sleep and they are plotted throughout the entire eight hours if one follows eeg through the night in this manner one sees a sequence of changes going from one to four and back to one that recur repeatedly throughout the entire night the points to make here that that the progression to stage four only appears twice and after that the progression is only to stage two in association with the repeated occurrence of stage one are the rapid eye movements is during these periods of rapid eye movements and stage one eeg the dreaming occurs the evidence for this is that when subjects are awakened during the rim periods they will remember dreaming with great vividness and clarity shortly after the subject goes to bed one sees the following indications of sleep onset a slowing in the frequency and an increase in the amplitude of the eeg and slow rolling eye movements which are typical of sleep onset approximately 10 or 15 minutes subsequent to sleep onset the subject enters stage 4 sleep as is indicated by the predominance of high amplitude slow wavy eg activity a high degree of electrodermal activity is also typical of this stage of sleep we will now arise the subject from stage 4 sleep steve steve yeah what was going through your mind just before i called him um nothing nothing very clear that i can remember do i have to think about it for a moment no i i really i really can't recall anything right clearly i don't think it stands out did you feel like there was something and you just realized yes that's right i feel like were there images no no images so you think this was spotlight okay you can go back to sleep now after 60 to 90 minutes of sleep the subject enters his first rapid eye movement period as is indicated by eeg activation the presence of conjugate rapid eye movements or rims and an inhibition of electromyographic activity this stage of sleep is commonly associated with a high amount of dream recall we will now arise the subject from a stage 1 rapid eye movement period see steve what was going through your mind just before i called you [Applause] i was um i was in a big uh i was in a crowd let me think um was it a was it a big guy was it a baseball game that's was it a baseball game and i was a um i was in the in the crowd at the baseball game watching them watching the game between the teams and i was um just watching watching the two teams play up i can't remember anything new and um do you remember the particular sequence of action you were watching at the time you were awakened i was paying particular attention to the uh the pitcher and how he was how he was throwing the ball um at the plate for the hitter but i wasn't i wasn't watching the ball uh particularly any particular way just watching him throw the ball watching his motion and i was attempting to uh i would i think slow down in my mind his his his motion so that it would look like he was throwing it in slow motion in my own mind but i wasn't able to do that very well studies of sleep utilizing the measurements that we have demonstrated and similar studies and experimental animals have enabled us to learn a great deal about the physiology of sleep with the aim of understanding how it functions and how it serves the biological economy of the mammalian organism another problem is the relationship between these physiological variables and dreaming to put it simply how is it that we see hear smell and touch things that aren't really there during these intriguing rim periods you