Sleep Physiology, Circadian Rhythms, Waking Performance and the Development of Sleep-Wake Therapeutics

Disturbances of the sleep-wake cycle are highly prevalent and diverse. The aetiology of some sleep disorders, such as circadian rhythm sleep-wake disorders, is understood at the conceptual level of the circadian and homeostatic regulation of sleep and in part at a mechanistic level. Other disorders such as insomnia are more difficult to relate to sleep regulatory mechanisms or sleep physiology. To further our understanding of sleep-wake disorders and the potential of novel therapeutics, we discuss recent findings on the neurobiology of sleep regulation and circadian rhythmicity and its relation with the subjective experience of sleep and the quality of wakefulness. Sleep continuity and to some extent REM sleep emerge as determinants of subjective sleep quality and waking performance. The effects of insufficient sleep primarily concern subjective and objective sleepiness as well as vigilant attention, whereas performance on higher cognitive functions appears to be better preserved albeit at the cost of increased effort. We discuss age-related, sex and other trait-like differences in sleep physiology and sleep need and compare the effects of existing pharmacological and non-pharmacological sleep- and wake-promoting treatments. Successful non-pharmacological approaches such as sleep restriction for insomnia and light and melatonin treatment for circadian rhythm sleep disorders target processes such as sleep homeostasis or circadian rhythmicity. Most pharmacological treatments of sleep disorders target specific signalling pathways with no well-established role in either sleep homeostasis or circadian rhythmicity. Pharmacological sleep therapeutics induce changes in sleep structure and the sleep EEG which are specific to the mechanism of action of the drug. Sleep- and wake-promoting therapeutics often induce residual effects on waking performance and sleep, respectively. The need for novel therapeutic approaches continues not at least because of the societal demand to sleep and be awake out of synchrony with the natural light-dark cycle, the high prevalence of sleep-wake disturbances in mental health disorders and in neurodegeneration. Novel approaches, which will provide a more comprehensive description of sleep and allow for large-scale sleep and circadian physiology studies in the home environment, hold promise for continued improvement of therapeutics for disturbances of sleep, circadian rhythms and waking performance

Veil and shroud: Eastern references and allegoric functions in the textile imagery of a twelfth-century gospel book from Braunschweig

This article discusses two medieval textile-inspired images that evoke the repeat of Eastern silk, and argues that so-called textile-pages in illuminated German manuscripts are not merely a sophisticated form of decoration, but that textile imagery generates iconological meaning in certain contexts and serves specific functions. The article proposes an iconological reading of two textile-pages in the Aegidien Gospels, a twelfth-century manuscript. It identifies one textile image as a visual commentary on the allegory of scripture as a veil of revelation, and the other as a representation of the shroud, which is shown to have mnemonic and contemplative functions in relation to the historic narrative and sacred truth of Christ’s death and resurrection. A kufesque inscription in the image of the shroud marks the depicted textile as an object of Eastern origin, and can be interpreted as a reference to the Holy Land in particular. By visually evoking the holy site of Christ’s tomb, the shroud image participates in a transfer of loca sancta from Jerusalem to twelfth-century Braunschweig, and in turn, connects with other holy sites that mark a larger sacred landscape of medieval Saxony. Interpreting the two textile-pages in the Aegidien Gospels from the viewpoint of recent approaches towards medieval court culture, textile imagery in this manuscript is shown to not be the result of the passive copying of textile patterns; rather, it is a distinct artistic contribution and form of appropriation that reflects the spiritual needs of the twelfth-century Saxon audience