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Published on: August 2, 2017
The dichotomy between low frequency and delta waves in human sleep: A reappraisal
Jean-Pol Lanquart1, Pasquale Nardone2, Philippe Hubain1
1Sleep Laboratory, Department of Psychiatry and Laboratory of Psychiatric Research, Hôpital académique Erasme, Université Libre de Bruxelles, Bruxelles, Belgium.
Background:
We present the results of an analysis of the low frequency (LF) (0.25-1Hz) and delta (1-4Hz) waves during human sleep. Our objective was to investigate whether LF and delta waves should be considered as separate entities.
Methods:
The slow-wave electroencephalogram (EEG) activity of 2 sets of 10 young, healthy volunteers was analysed utilising the rarely-used Lomb-Scargle periodogram. This method has advantages over the more commonly-used Fast Fourier Transform analysis.
Results:
During the night, the frequencies of the most powerful waves are concentrated in the 0.5-2Hz range and show a continuous tendency to shift towards slower frequencies during sleep.
Comparison With Existing Methods:
When considering the frequency dynamics of slow-wave activity below 3Hz, the unifying theory of LF and delta waves is more parsimonious than the idea that there is a different origin and regulation for the two sub-bands.
Conclusions:
The unifying theory of LF and delta waves is the simplest explanation for the slow-wave activity of the EEG below 3Hz. This finding is important for the clinical use of slow-wave activity.
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