Do Mice Dream of Stinky Cheese?
I’m a big fan of Sleep Review. It’s a good way to keep up with all things sleep related like technology developments, business prospects and scientific advances. It’s attractive and well-written. But a recent headline sent me into full-out grumpy old man mode.
The headline that caught my attention was “Genes That Regulate How Much We Dream.” The graphic showed a pair of mice, one a control mouse and the other with some genetic modification. My first thought was, “Wow. Dream reports from mice. This is truly groundbreaking!” Below the mice were pie charts (and anyone who knows me knows that I love pie charts) that showed a normal amount of REM sleep in the control mouse and no REM sleep in the experimental mouse. This made me wonder whether we would really hear about mouse dreams or just mouse REM sleep. Alas, when I followed the link to the article, the truth did not live up to the hype.
The title of the article was “Muscarinic Acetylcholine Receptors Chrm1 and Chrm3 Are Essential for REM Sleep” from the journal Cell Reports.1 While this falls far short of waking up mice and asking them about their dreams, it is an important step forward in our understanding of the control of REM sleep. In a careful series of studies that used synaptic inhibition of cholinergic neurons and CRISPR methods to knock out acetylcholine receptors, the authors provide compelling evidence that Chrm1 and Chrm3 are essential for REM sleep in mice. And if you think I have any idea of how this research is done and what Chrm1 actually is, you are completely mistaken. But I can assess the rigor of the research methods used and the evidence for the conclusions that are made.
You can tell by the title of the article that the authors are careful to accurately state the purpose and results of their paper. The headline? Not so much. It could have been, “Researchers Find Key Genes in Regulation of REM Sleep in Mice” or “Genetic Modifications Produce Mice that Do Not Have REM Sleep.” The key elements of my headlines are REM sleep and mice, and you will notice that in contrast to the Sleep Review headline, the word “dreams” is absent.
One reason for this is that the researchers did not measure dreams, did not claim to measure dreams and used mice as their experimental subject with the express knowledge that it would not provide an opportunity to collect dream reports.
The second part that irked me is that the headline conflated REM sleep and dreaming. Even in species that are able to give dream reports (that’s just us, so far), REM sleep and dreaming are not the same thing. David Foulkes has repeatedly written that REM is neither necessary nor sufficient for dreaming2, a claim supported by many studies including one showing continued dreaming despite pharmacological suppression of REM sleep.3 If mice dream, and I’m more than happy to agree that they do if presented with some evidence, I’m guessing that the knockout mice continue to have dreams despite an absence of REM. But, as I have said, the research does not show this. Yet.
The reason I launched into full grumpy old man mode is that the headline is misleading and supports claims that the media provides “fake news.” If you have 20 minutes to spare from cat videos, I strongly recommend a blistering commentary from John Oliver4 that focuses on the wide discrepancy between “Good Morning America” hype and the actual claims of the research that is reviewed. There is a section in the middle that focuses on animal research and features a pair of champagne drinking rats. This alone is worth the effort to watch the video.
Science is awesome. But using misleading headlines to capture gullible viewers is not. We still don’t know if mice dream of stinky cheese, or if they dream at all.
- Niwa Y, Kanda GN, Yamada RG et al., (2018), Muscarinic acetylcholine receptors Chrm1 and Chrm3 are essential for REM sleep. Cell Reports 24, 2231–2247
- Foulkes, D. (1993). Dreaming and REM sleep. Journal of Sleep Research, 2(4), 199-202.
- Oudiette D, Dealberto, M-J, Uguccioni G, et al. (2012). Dreaming without REM sleep. Consciousness and Cognition, 21(3), 1129-1140.
- Scientific Studies: Last Week Tonight with John Oliver, https://www.youtube.com/watch?v=0Rnq1NpHdmw (accessed 8/30/18)