Rn. Kingshott et al., The effect of sleep fragmentation on cognitive processing using computerized topographic brain mapping, J SLEEP RES, 9(4), 2000, pp. 353-357
Topographic brain mapping of evoked potentials can be used to localize abno
rmalities of cortical function. We evaluated the effect of sleep fragmentat
ion on brain function by measuring the visual P300 waveform using brain map
ping. Eight normal subjects (Epworth Score +/- SD: 5 +/- 3) underwent tone-
induced sleep fragmentation and undisturbed study nights in a randomized cr
oss-over design. Study nights were followed by topographic brain mapping us
ing a visual information processing test and concurrent event-related poten
tials. Experimental sleep fragmentation did not significantly increase obje
ctive daytime sleepiness or lower cognitive performance on a battery of cog
nitive function tests (all P greater than or equal to 0.1). There were no s
ignificant topographical delays in P300 latencies with sleep fragmentation
(all P > 0.15). However, at sites Fz, F4, T3, C3, Cz and C4 the P300 amplit
udes were reduced significantly after sleep fragmentation (all P < 0.05). A
reduction in P300 amplitude has previously been interpreted as a decrease
in attention. These reductions in P300 amplitudes with sleep fragmentation
in frontal, central and temporal brain areas suggest that sleep fragmentati
on may cause a broad decrease in attention. Sleep fragmentation did not del
ay P300 latencies in any brain area, and so does not explain the delay in P
300 latencies reported in sleep apnoeics.