Study Participant Demographics Design EEG
First Author Year Published Study type Number of participants Participant sex Participant age range Type of participants Simulation of hypoxia Exposure time (mins) FiO2 (%) PiO2 (kPa) SpO2 (%) Hypoxia classification Other analysis techniques Frequency analysis
Moderate; Severe Evoked potentials, Source localisation, Quantitative analysis techniques (BIS, approximate entropy, Lempel-Ziv Complexity) apha % change alpha beta % change beta delta % change delta theta % change theta Others
Agadzhanian 1971 Experimental cohort study 45 100% Male 20–30 Healthy volunteers Inhaled hypoxic gas mixture 2 60 Severe Decreased Decreased Increased at SpO2 < 75% Increased at SpO2 < 75%
Aleksandrov 2001 Experimental cohort study 9 100% Male 22–25 Healthy volunteers Inhaled hypoxic gas mixture   70 Severe Decreased Increased
Alekseev 1984 Experimental cohort study 41 100% Male 23–56 Healthy volunteers Hypobaric chamber to simulate 5,000 m altitude 30 21 10 Moderate Increased Increased
Baciu 1964 Experimental cohort study 14 Healthy volunteers Closed loop with scrubber 44,684 6.05 6.1 70 Severe Decreased Increased Increased
Balioz 2012 Experimental cohort study 24 100% Male 18–26 Athletes, swimmers and skiers Inhaled hypoxic gas mixture 25 10 9.5 74 Severe Decreased -29.4% No change Increased 5.2%
Bertha 1964 Experimental cohort study 34 88% Male; 12% Female 20–51 Healthy pilots and parachutists Inhaled hypoxic gas mixture 6.5 6 5.7 Severe Decreased Increased Increased
Burykh 2002 Experimental cohort study 18 100% Male 18–39 Healthy volunteers  Inhaled hypoxic gas mixture 15 8 7.6 67.5 Severe Increased Increased Dominant alpha waves; decreased spindle waveforms
Burykh 2005 Experimental cohort study 29 100% Male 18–30 Healthy volunteers Inhaled hypoxic gas mixture   15 8 8 Severe Decreased Increased Decreased Increased
Burykh 2007 Experimental cohort study 29 100% Male 18–30 Healthy volunteers Inhaled hypoxic gas mixture 15 8 7.6 Severe Decreased Increased Increased Increased
Burykh 2007 Experimental cohort study 16 100% Male 18–40 Healthy volunteers Inhaled hypoxic gas mixture   25 8; 12 7.6 (at FiO2 8%); 11.4 (at FiO2 12%) Severe at FiO2 8%; Moderate at FiO2 12% Total spectral power increase related to level of hypoxia
Burykh 2008 Experimental cohort study 16 100% Male 18–40 Healthy volunteers Inhaled hypoxic gas mixture 25 8; 12 7.6 (at FiO2 8%); 11.4 (at FiO2 12%) Severe at FiO2 8%; Moderate at FiO2 12% EEG spectral power increased during hypoxic exposure
Burykh 2011 Experimental cohort study 55 100% Male 20–40 Healthy volunteers Inhaled hypoxic gas mixture   25 8 8 56 Severe Increased Increased
Burykh 2020 Experimental cohort study 12 100% Male Healthy volunteers Inhaled hypoxic gas mixture 25 8 7.6 Severe Increased 30.9% Increased 302.7% Increased 287.4% Dominant alpha waves
Chatelier 1971 Experimental cohort study 203 Trainee pilots Hypobaric chamber to simulate 10,636 m, 9,144 m and 7,924 m altitudes 1.3,  2.4, 13.1 21 5 (after 1.3 min exposure); 6.3 (after 2.4 min exposure); 7.5 (after 13.1 min exposure) Severe at all exposures Increased Increased No EEG changes at 7,924 m
Chen 2020 Experimental cohort study 12 100% Male 20–25 Healthy students Inhaled hypoxic gas mixture 600 12 11.4 Moderate Increased in frontal, parietal and temporal lobes 31.0% Increased 29.6% EEG spectral power increased during hypoxic exposure
Decroix 2018 Randomised placebo controlled counter balanced double blinded cross over study  20 Healthy students Normobaric hypoxic chamber 30 12.7 12.1 Moderate Increased
Ding 2005 Experimental cohort study 3 100% Male Healthy student volunteers Inhaled hypoxic gas mixture to simulate 3,500 m altitude 30 21 12.5 Moderate Lempel-Ziv complexity and approximate entropy values increaed with hypoxia
Eckert  2005 Experimental cohort study 11 55% Male; 45% Female Healthy volunteers Inhaled hypoxic gas mixture 30 9 8.6 82.2 Moderate Reduced P1 (32.4%) and P2 (20.2%) amplitudes (positive slow waves) of respiratory-related evoked potentials
Edlinger 2005 Experimental cohort study 10 50% Mlale; 50% Female 26–57 Healthy volunteers Hypobaric chamber to simulate 990 m and 2,700 m altitudes 6 21 19.2 (at 990 m); 17.9 (at 2,700 m) Moderate at both altitudes Decreased Loss of correlation between EEG and cardio changes with increased altitude
Engel 1945 Experimental cohort study 10 Medical students and staff members Hypobaric environment 180 100 (at 11,887–12,954 m); 21 (at 3,048–4,876 m) 11.7 (at both altitudes) Moderate at both altitudes Increased shift to lower frequency waves at increasing amplitudes
Forster 1975 Experimental cohort study 7 100% Male Healthy volunteers Brought to higher altitude - 4,300 m  150 21 11.1 Moderate No change in EEG noted in all subjects
Gazivoda 1971 Experimental cohort study 43 Healthy pilots Hypobaric chamber to simulate 5,500 m altitude 20 21 10.6 Moderate Increased in 15 subjects No EEG changes seen in 21 subjects
Gora 1988 Experimental cohort study 22 100% Male 18–20 Healthy volunteers Inhlaed hypoxic gas mixture   30 10.5 9.9 Severe Increased Increased
Guger 2005 Experimental cohort study 10 50% Male; 50% Female 26–57 Healthy volunteers Brought to higher altitude 6 21 14 Moderate Increased 15.0% Increased 30.0%
Guger 2008 Experimental cohort study 10 100% Male 21–30 Healthy  volunteers Hypobaric chamber to simulate 4,000 m altitude 6 21 11.6 83.8 Moderate Unchanged during first hour; Increased after 11–13 hours 46.1% Increased 64.5%
Held 1976 Experimental cohort study 25 100% Male 23–45 Healthy volunteer Hypobaric chamber to simulate 5,800 m altitude 45 21 10.2 Moderate Decreased Increased Increased Increased
Holmberg 1953 Experimental cohort study 9 47–53 Inhaled hypoxic gas mixture 8 6.5 6.2 62 Severe Moderate decrease in EEG amplitudes - no note on which frequencies
Hu 2006 Experimental cohort study 5 100% Male 22 Healthy volunteers Inhaled hypoxic gas mixture to simulate 3,500 m altitude 25 21 12.5 Moderate Hypoxic and normal EEGs have distinguishable differences - no note on these exact differences
Ikeda 2009 Experimental cohort study 11 82% Male; 18% Female 20–46 Self-defence force volunteers Hypobaric environment to simulate 7,620 m altitude 5 21 6.6 69 Severe No change in BIS value with a hypobaric hypoxia exposure (SpO2 69%) compared to hypobaric normoxia and sea level exposures
Iwama 1950 Experimental cohort study 4 Healthy students Inhaled hypoxic gas mixture 6 45,236 8.1 Severe Decreased Increased
Jernajczyk 2006 Experimental cohort study 12 42% Male; 58% Female 26–32 Healthy volunteers Rebreathing from a 5 L bag of room air 7 21 75 Moderate Lempel-Ziv Complexity increased in subjects who experienced anxiety. No appreciable change in Lempel-Ziv Complexity in subjects who were not anxious. EEG frequencies remained unchanged at SpO2 75% Variable changes
Kaufman 1993 Experimental cohort study 13 100% Male 19–24 Healthy volunteers Hypobaric environment to simulate 4,300 m altitude 720 21 11.1 Moderate Decreased -6.7% Increased spindal waveforms
Kida 1993 Experimental cohort study 38 100% Male 22–40 Healthy volunteers Hypobaric environment to simulate 3,000 m, 4,000 m, 5,000 m, 6,000 m altitudes 45 21 12.8 (at 3,000 m); 11.6 (at 4,000 m); 10.0 (at 5,000 m); 8.6 (at 6,000 m) 63.4 (at 6,000 m) Moderate at 3,000 m, 4,000 m and 5,000 m; Severe at 6,000 m Both negative and positive slow waves of auditory evoked potentials dcreased in amplitude with increasing altitude
Konig 2004 Experimental cohort study 13 54% Male; 46% Female 24–28 Healthy volunteers Inhaled hypoxic gas mixture 3 9 8.6 71 Severe Decreased Increased Increased
Kraaier 1988 Experimental cohort study 36 100% Male 18–27 Healthy volunteers Hypobaric environment 10 21 8.4 70 Severe Significantly decreased -20.6% Significantly increased 34.7% Significantly increased 17.3%
Li 2016 Experimental cohort study 5 100% Male 23–26 Graduate students Inhaled hypoxic gas mixture 33 13 12.4 88.3 Moderate Increased Increased gamma activity
Luft 1956 Experimental cohort study 2 100% Male Hypobaric environment 0.2 100 2.9 15 Severe Increased Increased No specific EEG changes noted upon loss of participant comprehension
Malle 2016 Randomised trial 86 100% Male Inhaled hypoxic gas mixture 3 6 5.7 77.1 Severe No statistically significant EEG changes from baseline
Miszczak 1975 Experimental cohort study 10 100% Male 27–30 Healthy volunteer Inhaled hypoxic gas mixture 20 8 7.6 Severe Decreased amplitude and latency of auditory evoked potentials
Ozaki 1995 Experimental cohort study 15 67% Male; 33% Female 19–25 Healthy students High altitude chamber to simulate 4,000 m, 5,000 m, 6,000 m altitudes 25 21 11.6 (at 4,000 m); 10.0 (at 5,000 m); 8.6 (at 6,000 m) Moderate at 4,000 m and 5,000 m; Severe at 6,000 m After return to sea level, both theta and alpha activity decreased 
Papadelis 2007 Experimental cohort study 10 50% Male; 50% Female 21–41 Healthy volunteers Hypobaric environment to simulate 7,620 m, 6,096 m, 4,572 m altitudes 90 21 6.6 (at 7,620 m); 8.5 (at 6,096 m); 10.7 (at 4,572 m) Severe at 7,620 m and 6,096 m; Moderate at 4,572 m Significantly increased 22.2% increase at 7,620 m. Percentage increase at other altitudes not stated Significantly increased 23.8% at 7,620 m. Percentage increase at other altitudes not stated
Pokorski 2003 Experimental cohort study 3 33% Male; 67% Female 24–32 Healthy volunteers Rebreathing from a 5 L bag of room air 4.9 21 73 Severe Decreased -40.5% Decreased -17.2% Increased 16.5% Most pronounced changes in alpha activity
Prast 1948 Experimental cohort study 109 17–37 Healthy volunteers Inhaled hypoxic gas mixture 7.6 7.2 Severe Increased Increased
Pretorius 2006 Experimental cohort study 23 57% Male; 43% Female 22–32 Healthy student volunteers Hypobaric environment to simulate 3,657 m 45 21 12.2 88.7 Moderate Increased No statistically significant correlation between theta activity and amnesia
Ramadan 2020 Experimental cohort study 10 100% Male 24–33 Healthy student volunteers Hypobaric environment 15 15; 18; 21 14.3 (at FiO2 15%); 17.1 (at FiO2 18%); 20 (at FiO2 21%) Moderate at all exposures Decreased in frontal and central cortices (theta+alpha)/(alpha+beta) and theta/beta ratios decreased with hypoxia
Rebuck 1976 Experimental cohort study 6 100% Male 25–42 Healthy volunteers Rebreathing circuit 15 21 72 Severe Decreased
Remond 1960 Experimental cohort study 52 100% Male 18–35 Healthy trainnee and qualified pilots Inhaled hypoxic gas mixture 5 70 Severe Increased: bursts of delta waves in 21 subjects; continuous increase in delta activity 16 subjects Increased No EEG changes in 2 subjects
Rice 2019 Experimental cohort study 60 50% Male; 50% Female Student naval aviators, flight officers and flight surgeons Rebreathing mask to simulate 7,620 m altitude 35 21 6.6 76 Severe Significantly decreased Significantly decreased Significantly increased Significant increase in gamma activity; 37% of subjects failed to recognise they were hypoxic
Rozhkov 2009 Experimental cohort study 11 100% Male 25–34 Healthy volunteers Inhaled hypoxic gas mixture 20 8 7.6 35–65 Severe Increased density of EEDS foci in hypothalamus, thalamus, pons, temporal lobe and limbic system Increased Increased Increased
Rozhkov 2021 Experimental cohort study 41 100% Male 19–45 Healthy volunteers Inhaled hypoxic gas mixture 40 8 7.6 Severe Decreased temporal EEG activity; no significant change in spatial EEG potenetials
Saletu 1984 Double-blind placebo-controlled trial 10 100% Male 20–30 Healthy volunteers Inhaled hypoxic gas mixture 23 11.2 10.6 Moderate Decreased Increased Increased
Saletu 1987 Double-blind placebo-controlled trial 15 47% Male; 53% Female 21–41 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Decreased -23.0% Increased 157.1% Increased 1.5% Increased 1.5%
Saletu 1989 Double-blind placebo-controlled trial 20 24–34 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Increased Increased Increased Total spectral power significantly increased with hypoxia almost over the whole cortex
Saletu 1990 Double-blind placebo-controlled trial 16 50% Male; 50% Female 22–44 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Significantly decreased Decreased Increased Increased
Saletu 1990 Double-blind placebo-controlled trial 12 58% Male; 42% Female 24–41 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Decreased Increased Increased
Saletu 1992 Double-blind placebo-controlled trial 18 67% Male; 33% Female 20–34 Healthy volunteers Inhaled hypoxic gas mixture 23 8.6; 9.8 8.2 (at FiO2 8.6%); 9.3 (at FiO2 9.8%) Severe at both exposures Significantly decreased with moderate hypoxia; more marked decrease with severe hypoxia Significantly decreased
Saletu 1994 Double-blind placebo-controlled trial 16 100% Male 23–35 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 81 Moderate Decreased Increased Increased
Saletu 1994 Double-blind placebo-controlled trial 18 50% Male; 50% Female 20–38 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 71.5 Severe Significantly decreased Increased at later stages of hypoxia Decreased Decreased
Saletu 1995 Double-blind placebo-controlled trial 18 50% Male; 50% Female 20–38 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Significantly decreased Increased beta activity
Saletu 1996 Double-blind placebo-controlled trial 20 55% Male; 45% Female 19–34 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Significantly decreased Increased Significantly increased Significantly increased Reduced delta/theta  ratio with hypoxia
Saletu 1996 Double-blind placebo-controlled trial 16 56% Male; 44% Female 21–34 Healthy volunteers Inhaled hypoxic gas mixture 23 9.8 9.3 Severe Significantly decreased Increased Increased Increased Increased delta/ theta ratio with hypoxia
Schaffler 1986 Experimental cohort study 8 100% Male Healthy volunteers Inhaled hypoxic gas mixture 20 10.5 9.98 Severe Decreased -10.5% Increased 15.5% Decreased -19.0% Decreased -9.0%
Schellart 2001 Experimental cohort study 14 86% Male; 14% Female 18–52 Healthy volunteers Inhaled hypoxic gas mixture 9.5 10 9.5 67.2 Severe Decreased Increased Significantly increased
Schneider 2009 Experimental cohort study 20 70% Male; 30% Female Healthy volunteers Inhaled hypoxic gas mixture 40 12.7 81.38 Moderate No change Increased   Clear widespread increased spectral power within frontal cortex
Seech 2020 Experimental cohort study 40 67.5% Male; 32.5% Female Healthy volunteers Hypobaric environment 27 10.6 10.1 75 Moderate Reduced P3a amplitude (positive slow wave component) of auditory evoked potentials within the first 9 mins of hypoxic exposure. Reduced auditory processing with hypoxia
Shi 1983 Experimental cohort study 18 67% Male; 33% Female 18–23 Young athletes Hypobaric chamber to simulate 5,000 m and 6,000 m altitudes 240 21 10 (at 5,000 m), 8.6 (at 6,000 m) Moderate at 5,000 m; Severe at 6,000 m Decreased at 5,000 m Increased at 5,000 m Increased at 7,500 m Increased at 7,500 m
Shi 1987 Experimental cohort study 36 83% Male; 17% Female 16–23 Young soldiers and athletes Inhaled hypoxic gas mixture AND hypobaric chamber to simulate 5,000 m, 6,000 m, 7,500 m altitudes 4 8.4 (inhaled hypoxic gas mixture) AND 21 (at different altitudes) 8.0 (at FiO2 8.4%); 10.0 (at 5,000 m, FiO2 21%); 8.6 (at 6,000 m, FiO2 21%); 6.7 (at 7,500 m, FiO2 21%) Severe at FiO2 8.4%, 6,000 m and 7,500 m; Moderate at 5,000 m Decreased Increased
Shi 2017 Experimental cohort study 4 100% Male 26–45 Professional divers Hypobaric environment to simulate 3,000 m, 4,000 m, 5,200 m altitudes 120 21 13.4 (at 3,000 m); 11.6 (at 4,000 m); 9.7 (at 5,200 m) Moderate at 3,000 m and 4,000 m; Severe at 5,200 m Significantly decreased
Sieker 1960 Experimental cohort study 22 100% Male Healthy volunteers Inhaled hypoxic gas mixture 10 10 9.5 73.1 Severe Decreased Increased
Sokolov 1970 Experimental cohort study 8 18–20 Healthy volunteers Hypobaric chamber to simulate 4,000 m, 5,000 m, 6,000 m altitudes 21 11.6 (at 4,000 m); 10 (at 5,000 m); 8.6 (at 6,000 m) Moderate at 4,000 m and 5,000 m; Severe at 6,000 m Decreased in frontal and parietal cortices Increased in frontal and parietal cortices Increased in frontal and parietal cortices
Soroko 1994 Experimental cohort study 32 100% Male 20–22 Healthy volunteers Inhaled hypoxic gas mixture   15 8.9 8.5 57 Severe Decreased Increased
Soroko 2002 Experimental cohort study 68 100% Male 18–19 Healthy volunteers Ascending to 3,600 m altitude 43200 21 12.3 Moderate Increased 56.9% No change No change Increased in frontal and parietal cortices 40.0%
Soroko 2005 Experimental cohort study 143 18–30 Healthy volunteers Inhaled hypoxic gas mixture 20 8; 9 7.6 (at FiO2 8%); 8.6 (at FiO2 9%) 57.5 Severe at both altitudes Decreased Increased Increased
Soroko 2007 Experimental cohort study 37 25–34 Healthy volunteers Inhaled hypoxic gas mixture 22.5 8 7.6 62 Severe Redistribution of EEDS foci. Increased density in hypothalamus, forebrain and limbic system Increased Increased
Soroko 2012 Experimental cohort study 76 100% Male 20–40 Healthy volunteers Inhaled hypoxic gas mixture 32.5 8; 9 7.6 (at FiO2 8%); 8.6 (at FiO2 9%) 60 Severe at both altitudes Dissociation between the frontal, temporal and occipital regions
Tanaka 1982 Experimental cohort study 30 24–37 Healthy members of mountaineering team Hypobaric chamber to simulate 4,000 m and 6,000 m altitudes 65 21 13 (at 4,000 m); 10 (at 6,000 m) Moderate at both altitudes No EEG changes at 4,000 m
Van der Post 2002 Experimental cohort study 12 67% Male; 33% Female 19–27 Healthy volunteers Inhaled hypoxic gas mixture 130 80 Moderate Decreased -9.2% Decreased at SpO2 < 90%; Increased at SpO2 80%   -3.6%; Percentage increase not stated Decreased at SpO2 90%; Increased at SpO2 80%   -7.2%; Percentage increase not stated
Van der Worp 1991 Experimental cohort study 10 100% Male 20.3–27.3 Healthy volunteers Rebreathing circuit 22 70 Severe Increased in low alpha frequency range (7.7–9.2 Hz); Deceased in high alpha frequency range (10.4–12.4 Hz) No significant EEG changes seen at SpO2 70–80%
Wang 2015 Experimental cohort study 19 47% Male; 53% Female Healthy student volunteers Inhaled hypoxic gas mixture 5 6.7 67.5 Severe No change No change No change No change No change in delta/alpha ratio
Zani 2020 Experimental cohort study 10 60% Male; 40% Female 19–27 Healthy volunteers Inhaled hypoxic gas mixture 240 12.5 11.9 Moderate Increased over the parietal and occipital cortices
Zhang 2016 Experimental cohort study 3 100% Male Healthy volunteers Inhaled hypoxic gas mixture to simulate 3,500 m altitude 3 21 12.5 Moderate Reduction in phase locking value with hypoxia