Quantified Sleep: Self-Tracking Technologies and the Reshaping of 21st-Century Subjectivity.

Taking sleep-tracking as its case study, this article seeks to theorise the understandings of the self that are at stake in the the Quantified Self (QS) movement and everyday self-tracking practices by bringing together a cultural theorist's and a philosopher's perspectives. We situate the rise of sleep-tracking practices within the sleep crisis discourse, namely, the sense that in today's society sleep disorders are on the rise and sleep deprivation is rife. Through analyses of self-trackers' blogs about sleep, sleep-tracking technologies' marketing information, and the functionalities of these devices and apps, we argue that the drive to self-improve at the heart of self- and sleep-tracking props up an understanding of the self centred around achievement. This understanding ends up devaluing sleep and risks contributing to the sleep crisis. We show how these paradoxes can be further understood from an epistemological perspective. Self- and sleep-tracking are arguably practices that seek to obtain knowledge by trading referential expert knowledge for self-referential nonexpert knowledge and that strive for self-optimisation by self-sabotaging achievement subjectivity. We conclude that the use of self-tracking technologies magnifies what is essentially a crisis of subjectivity.