'In praise of ...REM'

The Guardian, 25 November 2011 referred to the article in Current Biology

No, not the late-lamented band, whom we praised a few weeks ago. We refer to the state in which the twitch of the closed eye betrays the unshackling of the imagination. REM is something shared with many animals. Humans can't even claim to do more than the rest – a glance at the REM league table suggests armadillos dream far bigger dreams. The unlikely connection between the flittering iris and the unconscious mind's eye was first discerned in the 1950s, and was established fact before long. Ever since, we have known we owe our nightly flights of fancy to this distinctive sleep phase which features a complex chemistry and irregular breathing as well as the rapid eye movement itself. We owe to it, too, the whole cultural story of dreaming which stretches from Sumerian myths to Freudian speculation by way of the Bible itself. Throughout, there's been speculation as to why we dream in the first place, and yet most of the myriad "theories" advanced remain just that. Now a paper in Current Biology sheds a little light on what happens in the dark hours. The researchers showed subjects images that pulled on the heartstrings before allowing half – and depriving the rest – of a proper sleep. The next day they saw the images again, and scans revealed that while the raw emotional centres non-sleepers brains still buzzed in response, the sleepers' reasoning apparatus kicked in. Sleep seems to lay demons to rest, or at least allow them to be approached in a dispassionate spirit. Sweet dreams indeed.

Perhaps an example of the process whereby  an idea which starts off being ignored,  then controversial and rejected  finally becomes mainstream and part of the background with no one quite sure where it came from but just obvious when you think about it. Joe's theory links the mystery of dreaming as the leader article says with a rational EXPLANATION so joining two pars of our conscious lives - wondering and digesting satisfying answers.

But as it’s well past midnight I'd better get some rem in myself

Harold

If you go to The Guardian web site and search 'In praise of rem' there is a  link to the Current Biology

reference:

REM Sleep Depotentiates Amygdala Activity to Previous Emotional Experiences

Authors

Els van der Helm, Justin Yao, Shubir Dutt, Vikram Rao, Jared M. Saletin, Matthew P. Walker

 See Affiliations

Sleep and Neuroimaging Laboratory, Department of Psychology, University of California, Berkeley, Berkeley, CA 94720-1650, USA Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-1650, USA Corresponding author

• Highlights

► Sleep decreases amygdala activity to prior waking emotional experiences ►The amygdala decrease is associated with reestablished prefrontal connectivity ►These neural changes are accompanied by overnight reductions in subjective reactivity ►Reductions in both brain and behavioral reactivity are associated with REM physiology

Summary

Clinical evidence suggests a potentially causal interaction between sleep and affective brain function; nearly all mood disorders display co-occurring sleep abnormalities, commonly involving rapid-eye movement (REM) sleep [1,2,3,4]. Building on this clinical evidence, recent neurobiological frameworks have hypothesized a benefit of REM sleep in palliatively decreasing next-day brain reactivity to recent waking emotional experiences [5,6]. Specifically, the marked suppression of central adrenergic neurotransmitters during REM (commonly implicated in arousal and stress), coupled with activation in amygdala-hippocampal networks that encode salient events, is proposed to (re)process and depotentiate previous affective experiences, decreasing their emotional intensity [3]. In contrast, the failure of such adrenergic reduction during REM sleep has been described in anxiety disorders, indexed by persistent high-frequency electroencephalographic (EEG) activity (>30 Hz) [7,8,9,10]; a candidate factor contributing to hyperarousal and exaggerated amygdala reactivity [3,11,12,13]. Despite these neurobiological frameworks, and their predictions, the proposed benefit of REM sleep physiology in depotentiating neural and behavioral responsivity to prior emotional events remains unknown. Here, we demonstrate that REM sleep physiology is associated with an overnight dissipation of amygdala activity in response to previous emotional experiences, altering functional connectivity and reducing next-day subjective emotionality.