On Tue, 29 Jun 1999, JL Edwards wrote:
:-)
:-) Thanks Val, but I'm still having a difficult time and I'm like a pitbull..
:-) won't let go till I understand so forgive me for another round of this.
:-)
:-) I understand that researchers are trying to determine if there is a built in
:-) biological clock and to rule out environmental cues, they must be removed.
:-) If I'm understanding correctly, whether it's constant bright light, constant
:-) subdued light, or constant darkness, people still undergo regular changes in
:-) physiology and sleep/awaken. However, I just don't understand how
:-) researchers can determine how long the cycle is when they are using one of
:-) the most powerful cues: bright light/subdued light/no light, in other words
:-) light/dark. It seems to me this is a confounding variable and that by
:-) manipulating light/darkness, they are manipulating and resetting the
:-) biological clock. How valid are the results, which range from 10 to 30 hours
:-) (average 25) and the newest results (24 hours, 11 minutes)? How are we to
:-) ever know with certainty how long the cycle NATURALLY occurs when it is
:-) studied in contrived situations with researchers controlling powerful light
:-) cues?
I have not read the complete research, but if the investigators kept the
light at a constant subdued level, then there would be no confounding, and
the natural circadian rhythm would show up. My guess is that they used
subdued light because bright light would make it too difficult to sleep
(overriding the natural clock), and not light would not allow the
participants to engage in any activity during their waking hours.
Joel
Joel S. Freund Phone: 501/575-4256
Department of Psychology FAX: 501/575-3219
216 Memorial Hall Internet: [EMAIL PROTECTED]
Fayetteville, AR 72701-1201
