Time for Bed

                Lonnie Shekhtman explains a study testing the question, “did caveman really get more sleep that we do?” Scientists from American, Mexican, and South African universities studied the sleep patterns of remote societies in Africa and Latin America. Given the isolation of the subjects, the scientists’ results are comparative to prehistoric ancestors. The study included 94 adults from Tanzania, Namibia, and Bolivia.

One professor mentioned within the article is Jerome M. Siegel from the University of California in Los Angeles. Dr. Siegel reported that subjects did not sleep more than average. Over the course of three years, no matter the region, participants slept on average 6.5 hours.

Researchers said that common explanations for sleep patterns in the tribes studied were refuted, such as light patterns. However, their results suggest a correlation between temperature and sleep for these societies. Dr. Siegel explains that since we are no longer as sensitive to temperature change given average living conditions.

During his time at University of Pennsylvania, Dr. Daniel Cavanaugh examined the output pathway of clock cells in Drosophila, or fruit fly. Within his research, Dr. Cavanaugh found that “PI cells are connected to the clock through a polysynaptic circuit extending from pacemaker cells to PI neurons.” In addition, results showed that “selective activation or ablation of just six DH44+ PI cells causes arrhythmicity.”

While Dr. Cavanaugh’s work is in Drosophila and not humans, his work towards networking the circadian rhythm relates to the study comparing the average human’s sleep to our prehistoric ancestor’s sleep. If the output pathway of the circadian rhythm responds to the selective activation of six DH44+ PI cells, then those cells (in a distant way) respond to outside cues. Based on Dr. Siegel’s study, the possible cue for prehistoric ancestors’ was temperature. Possibly temperature played a more critical role in activation, and the overall circadian rhythm, in our prehistoric ancestors than it does for us now.

While we are far from confirming the exact mapping of the circadian rhythm or having official proof that our ancestors did not sleep more than we do, sleep is still a critical part of life and is an important topic of study for future scientists.

Works Cited

Cavanaugh, Daniel J., Jill D. Geratowski, Julian R.a. Wooltorton, Jennifer M. Spaethling,

Clare E. Hector, Xiangzhong Zheng, Erik C. Johnson, James H. Eberwine, and

Amita Sehgal. “Identification of a Circadian Output Circuit for Rest:Activity

Rhythms in Drosophila.” Cell 157.3 (2014): 689-701. Web. 17 Sept. 2015

Shekhtman, Lonnie. “Did Caveman Really Get More Sleep than We Do?” The Christian  

            Science Monitor. The Christian Science Monitor, 16 Oct. 2015. Web. 16 Oct.

            2015.

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