A new study found that performance was significantly improved, despite a longer time awake, in the wake maintenance zone, a three-hour window of reduced sleep propensity that occurs shortly before the onset of melatonin secretion.  The results are published in the April 15 issue of the Journal of Clinical Sleep Medicine.  The study suggests that small misalignments of circadian phase may alter the timing of alertness and performance, and may contribute to sleep-onset insomnia complaints.  Furthermore, it may be possible to capitalize on the wake maintenance zone as a time of better neurobehavioral performance for people working non-standard or extended shifts.