Sleep in the blind mole rat Spalax ehrenbergi.
Level 5 - mechanism / opinion, no new human data
Animal physiological laboratory study
What was done
Continuous 24-hour recordings of electroencephalogram (EEG), electromyogram (EMG), and cortical temperature along with EEG spectral analysis were conducted in six wild-caught blind mole rats (*Spalax ehrenbergi*) after several months of laboratory adaptation.
What was found
Total sleep time comprised 52% of the 24-hour recording period, with REM sleep comprising 8%. Blind mole rats displayed a distinct polyphasic sleep-wake pattern with only a minor, inconsistent preference for sleep during the dark period. Slow-wave activity in non-REM sleep followed the polyphasic pattern and previous sleep-wake history. Transitions from non-REM to REM sleep involved power surges in theta and sigma EEG frequency bands that massively exceeded levels seen in other rodents.
Why it matters
This study shows that extreme subterranean adaptation and ocular atrophy do not substantially alter basic mammalian sleep amounts or homeostatic dynamics, despite distinct polyphasic architecture and pronounced pre-REM EEG power surges.
Limits
The study is limited to an animal model with a very small sample size (n = 6). Measurements were taken in a laboratory environment rather than natural subterranean burrows, and exact numerical metrics for EEG frequency power surges were not reported in the abstract.