EEG and sleep disturbances during dives at 450 msw in helium-nitrogen-oxygen mixture

Abstract

To study the effects of nitrogen addition to the breathing mixture on sleep disturbances at pressure, two dives were performed in which helium-nitrogen-oxygen mixture was used up to 450 m sea water (msw). In total, sleep of 12 professional divers was analyzed (i.e., 184 night records). Sleep was disrupted by compression and by stay at 450 msw: we observed an increase in awake periods and in sleep stages I and II and a decrease in stages III and IV and in rapid-eye-movement sleep periods. These changes, which were more intense at the beginning of the stay, began to decrease from the seventh day of the stay, but the return to control values was recorded only during the decompression at depths below 200 msw. These changes were equivalent to those recorded in other experiments with helium-oxygen mixture in the same range of depths and were independent of the intensity of changes recorded in electroencephalographic activities in awake subjects.

Selective modulation of cellular voltage-dependent calcium channels by hyperbaric pressure—a suggested HPNS partial mechanism

“…This may interfere with time processing and coincidence detection as well as motor and sensory functions in a manner similar to HPNS signs and symptoms. A slower rhythm at HP was indeed found in humans, where EEG waves shifted from α to θ patterns (Rostain et al, 1997). The same study also demonstrated sleep disturbances that were more prominent during the beginning of the compression, subsided later, and were abolished at decompression, suggesting both transient and reversible HP effect, similar to the results shown in our experiments.…”

“…By controlling partial-pressures of absorbed tissue gases while under pressure, these neurological problems, excluding HPNS, can be alleviated and even eliminated, leading to the notion that HPNS occurs due to effects of pressure per se (Abraini, 1997; Bennett, 1997). Deep sea divers (approximately >100 m), as well as animals exposed to hyperbaric pressure (HP), may experience HPNS, which in humans includes dizziness, nausea, tremors, vision, and auditory disturbances, decrements in locomotor activity (Tarasiuk and Grossman, 1990; Darbin et al, 2000) and intellectual performance (Logue et al, 1986; Vaernes et al, 1988; Overman et al, 1989; Abraini, 1997; Steevens et al, 1999), confusion, changes in EEG and sleep disorders (Rostain et al, 1997), myoclonus (Darbin et al, 2000), convulsions, and loss of consciousness.…”

Circadian Rhythm and Stress

“…Below 400 m using heliox (mix of helium and oxygen) or trimix (mix of oxygen, nitrogen and helium), the sleep disturbances aggravate further as SWS and REM continue to decrease and awakenings occur (Rostain et al 1997 ) . Sleep at hyperbaric pressure is highly disturbed, unaffected by the used gas mixture; sleeping patterns return to normal during recompression.…”

Sleep under extreme environments: Effects of heat and cold exposure, altitude, hyperbaric pressure and microgravity in space

“…At 300 m, SWS decreases and stage 2 increases [75,81,82]. Below 400 m, sleep continues progressively to deteriorate using oxygen-helium [75] or trimix mixtures [83]. Numerous awakenings are accompanied by increases of stages 1 and 2 at the expense of SWS.…”