Studies which have defined the duration of a blink are scarce. Stern, Walrath, and Goldstein (1984) distinguished endogenous blinks from non-blink closures which are associated with sleep onset for instance. Endogenous blinks are characterized by (i) the time from initiation of the lid movement to full eye closure which takes generally around 100 ms, (ii) the period during which the vision is occluded which lasts at most 300 ms, and (iii) the full reopening phase lasting around 100 ms. Capitalizing on this, it was assumed that the longest endogenous blinks last 500 ms.