Time spent awake

The effects of acute systemic dexamethasone administration on sleep structure have been investigated. Dexamethasone caused significant increases in REM latency, the percentage time spent awake, and the percentage time spent in slow-wave sleep. There were also significant reductions in the percentage time spent in REM sleep and the number of REM periods (SEDA-21, 413 97). 

Figure 15.6 The mean hourly distribution of wakefulness time (min/h) in orexin/ataxin-3 rats and wild-type littermates. Although over the 24 h period there is little total difference in the time spent in wakefulness, it is evident that the transgenic rats spend less time awake during the dark phase, which is denoted by the horizontal bar, especially at the photoperiod boundaries. Note, in particular, the difference at the end of the dark phase. The latter corresponds to a time of maximum orexin levels in the rat, and may be related to a circadian wakefulness signal. Asterisks designate those hours with a significant difference in wakefulness times between the genotypes (p < 0.05). Adapted from Beuckmann et al. (2004).

A 7-year-old boy arrives at the emergency department asleep in his father s arms. The boy s mother explains that the boy spent the night throwing up and experiencing severe diarrhea. She is concerned about the vomiting and his inability to stay awake. History indicates the boy was healthy yesterday, but became ill at dinnertime after spending time playing in the... 

In the suprachiasmatic and paraventricular nuclei VIP immunoreactivity increases during the dark period, when rodents are mostly awake, and decreases during the subsequent light period, when most of the time is spent in sleep (141,142). In addition, VIP immunoreactivity exhibits diurnal variations in the locus ceruleus nucleus and the periaqueductal gray matter. REM sleep depriva-... 

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