The position of the load, fulcrum, and effort are in different spots. In a first class lever, the fulcrum is between the load and effort. In a second class lever, the load is â¦between the force and fulcrum.
By the age of about 75, stage four sleep and delta waves may be entirely absent. In addition to a decrease in the incidence of delta waves during slow-wave sleep in the elderly, the incidence of temporal delta wave activity is commonly seen in older adults, and incidences also increase with age.
As the brain cools, the vapors condense, flow downward and then cool the heart which causes sleep. Still others claimed that toxins that poisoned the brain caused sleep (Lavie, 1993/1996). With the discovery of brain waves and later the discovery of electroencephalogram, the way sleep was studied changed forever.