Sleep is one of the topics of modern neuroscience that is still very far from understood. We know that it is essential for life and that almost all organisms take part in this behavior. Yet with it being so prevalent, we still do not really understand how it works. That is where the work of people like Dr. Cavanaugh comes into play. Loyola University Chicago Dr. Cavanaugh conducts research on circadian rhythms and sleep. Dr. Cavanaugh’s research places a focus on how exactly sleep and circadian rhythms function, by looking at the roles and interactions of various genes like CLOCK, PERIOD, TIME, CYCLE and many others. But those are not the only factors that contribute to sleep, there are also numerous hormones that can affect sleep and circadian rhythms.
But first, it is important to define sleep. One characteristic that defines sleep is a "rapidly reversible state." This means, that if an organism is truly in a state of sleep then it should be able to come out of that state very quickly. To be asleep also means that the organism must have reduced overall movement, as well as a reduced response to stimuli. Another key aspect that is critical for defining sleep in a research context is that if that organism is deprived of sleep for a certain period of time, then that same organism must respond by showing an increased drive for sleep as well as an increased time in that so-called sleep state.
Recently I had the pleasure of attending a talk by Dr. Cavanaugh on his research and learned that sleep is a very complex process in our body. From what he presented, there is a large emphasis in the world of neuroscience on developing a complex model that can account for the roles of all the various proteins and hormones that regulate sleep. While his findings are not complete, Dr. Cavanaugh and his research both imply that the complete model for sleep and circadian rhythms in the body are even far more complex than we can even imagine. With the scientific community currently believing the immensely complex nature of sleep, the findings by researchers at Caltech on jellyfish sleep poses some very interesting questions.
A Caltech research group conducted work on Cassiopia Jellyfish and determined that this species does in fact sleep. To determine this creature does in fact sleep, they conducted many tests. First, they monitored how many pulses of their bell a jellyfish did over a course of six days and nights. When the data was compared it was found that during nighttime the jellyfish pulsed their bell about 66% less than during the day. They also noticed 10-15-second-long periods where the jellyfish did not make any pulses at all, this behavior was not present at all during the day.
To test the “rapidly reversible” aspect of sleep the researchers would remove the base that the jellyfish was sleeping on. They found that reaction times were slower during the night when compared to during the day. They also noted that during night time when the base was removed, replaced immediately and then removed again within with very close proximity to the first removal, the reaction time for the second base removal was similar to those found during the daytime trials. This then suggests that after removing the base the first time the jellyfish was woken up.
The results of this study show that this species of jellyfish does indeed sleep. But what makes this significant is that jellyfish have a very primitive nervous system, they do not even have a brain. Jellyfish do not have a nervous system like most organisms, while they do have neurons, they are organized in a manner to form a “neural net.” It is astounding that an organism with such a barebones nervous system can still exhibit all of the same sleep behaviors that are to be expected from more complex organisms. This would then suggest that sleep is very primitive in nature. But, that should then raise questions as to why when we are trying to study sleep in more complex organisms we are still unable to deduce the underlying mechanisms. If sleep is as primitive and simple as the jellyfish model would suggest, that means the complex models being developed by Dr. Cavanaugh are, not incorrect, but overcomplicating the system. While humans are far more complex than a simple jellyfish, they both exhibit the same sleep behavior, and thus the underlying mechanism should not be radically different, and maybe a new simpler approach must be taken.
You can head over to the link below to read the “Scientific American” article that explains the Caltech jellyfish study.
No comments:
Post a Comment