New Methods for Studying Motility During Sleep

Abstract

The methods heretofore employed for investigating motility during sleep involved the continuous recording on a kymograph of the position of the bed-spring or the whole bed, by direct transmission to a writing lever, pneumatic transmission to a recording tambour, or electrical transmission to a signal magnet. The first 2 of these methods furnish a record of the frequency as well as of the magnitude of movement, the last one, only of frequency.

Although it has been shown repeatedly that one stirs and turns over several times per hour during sleep, it has never been determined how much time one spends in these movements, or by difference what part of the time given to sleep one really lies still. One of the new methods was developed to answer this question. A large tambour (one foot in diameter) was placed under the bed and connected to the bed-spring by means of a vertical rod. The tambour was supplied with inlet and outlet valves and wired in such a manner that the opening of either valve would break an electric circuit. When the sleeper moved the displacement of the bed-spring downward compressed the air in the tambour causing the outlet valve to open, and the displacement of the bed-spring upward rarified the air causing the inlet valve to open. The valves remained open, and the circuit broken during the entire movement. Through a relay in the circuit a Telechron electric clock was started and kept running during the movement, or else a clock that was running stopped and kept still. With 2 clocks both of these effects could be produced simultaneously. The first clock having been set at zero (12 o'clock) before going to bed, its reading next morning gives the time spent in movement during the night.