TABLE 2.
Heart rate variability parameters during a daytime nap in normobaric normoxia (NN) and normobaric hypoxia (NH15: FiO2 14.7, NH13: FiO2 12.5).
| Phase | N | RR (ms) | RMSSD (ms) | SD1 (ms) | PNS | HR (b.p.m.) | SD2 (ms) | SI | SNS | ||
|---|---|---|---|---|---|---|---|---|---|---|---|
| NN | Women | Pre | 8 | 985 ± 115 | 66.3 ± 48 | 47 ± 34 | 1 ± 1.84 | 61.6 ± 7.1 | 64.3 ± 25.7 | 8.2 ± 2.7 | −0.52 ± 0.92 |
| N2 | 8 | 1,024 ± 146 | 74.9 ± 43 | 53 ± 30 | 1.44 ± 1.79 | 59.8 ± 9.4 | 64.4 ± 14.8 | 7.8 ± 3.3 | −0.73 ± 1.16 | ||
| Pos | 8 | 938 ± 125 | 56.7 ± 46 | 40 ± 33 | 0.55 ± 1.81 | 65 ± 8.9 | 50.2 ± 22.1 | 10.8 ± 4 | 0.08 ± 1.21 | ||
| Men | Pre | 7 | 1,172 ± 170 | 55 ± 34 | 39 ± 24 | 1.54 ± 1.76 | 52.1 ± 6.9 | 52.6 ± 15.7 | 8.7 ± 3.9 | −1.05 ± 1.13 | |
| N2 | 7 | 1,230 ± 157 | 48.7 ± 24 | 35 ± 17 | 1.64 ± 1.32 | 49.4 ± 5.5 | 49.1 ± 19.6 | 8.5 ± 2.7 | −1.26 ± 0.75 | ||
| Pos | 7 | 1,083 ± 95 | 42.8 ± 21 | 30 ± 15 | 0.77 ± 0.97 | 55.8 ± 5 | 54 ± 23.3 | 9.5 ± 3.7 | −0.65 ± 0.74 | ||
| All | Pre | 15 | 1,072 ± 168 | 61 ± 41.2 | 43.2 ± 29.2 | 1.25 ± 1.76 | 57.2 ± 8.4 | 58.8 ± 21.8 | 8.4 ± 3.2 | −0.77 ± 1.02 | |
| N2 | 15 | 1,120 ± 180 | 62.7 ± 36.6 | 44.4 ± 26 | 1.53 ± 1.54 | 54.9 ± 9.3 | 57.3 ± 18.4 | 8.1 ± 2.9 | −0.98 ± 1 | ||
| Pos | 15 | 1,006 ± 132 | 50.2 ± 36.2 | 35.6 ± 25.6 | 0.65 ± 1.43 | 60.7 ± 8.5 | 52 ± 21.9 | 10.2 ± 3.8 | −0.26 ± 1.05 | ||
| NH15 | Women | Pre | 8 | 876 ± 122 | 42.1 ± 21 | 30 ± 15 | 0.25 ± 1.75 | 69.6 ± 9.1* | 61.8 ± 28.9 | 9 ± 3.4 | 0.15 ± 1.02 |
| N2 | 7m | 940 ± 165 | 64.7 ± 43 | 46 ± 30 | 0.75 ± 1.91 | 65.6 ± 11.4 | 62.3 ± 23.4 | 9.4 ± 4.5 | −0.07 ± 1.5 | ||
| Pos | 7m | 795 ± 109* | 26.6 ± 17 | 19 ± 12 | −1 ± 0.94* | 76.6 ± 9.6** | 37.8 ± 18.9 | 15.2 ± 6.5 | 1.61 ± 1.6*A | ||
| Men | Pre | 6m | 1,135 ± 185 | 53.8 ± 37 | 38 ± 26 | 1.28 ± 1.88 | 53.9 ± 8.2 | 63.6 ± 19.2 | 7.7 ± 2.5 | −1.02 ± 0.94 | |
| N2 | 6m | 1207 ± 123 | 51.7 ± 28 | 37 ± 20 | 1.54 ± 1.37 | 50.1 ± 4.7 | 67.9 ± 26.9 | 7.6 ± 2.7 | −1.28 ± 0.68 | ||
| Pos | 6m | 1,036 ± 86 | 38.3 ± 25 | 27 ± 18 | 0.4 ± 1.03 | 58.3 ± 5.3 | 55.7 ± 26.6 | 10.4 ± 4.7 | −0.31 ± 0.85 | ||
| All | Pre | 13 | 987 ± 197* | 47.5 ± 28.9 | 33.7 ± 20.5 | 0.69 ± 1.81 | 62.9 ± 11.6* | 62.6 ± 24.3 | 8.4 ± 3 | −0.36 ± 1.13 | |
| N2 | 13 | 1,063 ± 198 | 58.7 ± 35.7 | 41.6 ± 25.3 | 1.12 ± 1.67 | 58.4 ± 11.8 | 64.9 ± 24.2 | 8.6 ± 3.7 | −0.63 ± 1.31 | ||
| Pos | 13 | 906 ± 157**A | 32 ± 20.7 | 22.7 ± 14.6 | −0.36 ± 1.19*A | 68.2 ± 12.2*A | 46.1 ± 23.7 | 13 ± 6 | 0.73 ± 1.6A | ||
| NH13 | Women | Pre | 8 | 781 ± 85** | 30.5 ± 17 | 22 ± 12* | −0.96 ± 0.81** | 77.5 ± 7.9** | 43.9 ± 15.8 | 13.4 ± 4.5 | 1.4 ± 1.14** |
| N2 | 8 | 797 ± 168** | 36.8 ± 32 | 26 ± 23* | −0.73 ± 1.64** | 78.2 ± 16** | 48.4 ± 31.4 | 16.6 ± 12.5* | 1.97 ± 2.96** | ||
| Pos | 8 | 708 ± 93** | 15.7 ± 11 | 11 ± 8* | −1.77 ± 0.77** | 86 ± 10.7**A | 31.3 ± 17.5 | 19.3 ± 7.1* | 2.95 ± 1.61**A | ||
| Men | Pre | 7 | 1,010 ± 126** | 46.8 ± 28* | 33 ± 20 | 0.45 ± 1.29 | 60.2 ± 7.1 | 81 ± 41.8 | 7.7 ± 2.6 | −0.55 ± 0.82 | |
| N2 | 7 | 1,048 ± 103** | 52.3 ± 32* | 37 ± 22 | 0.77 ± 1.31 | 57.7 ± 5.2* | 93 ± 45.6* | 7 ± 3.5 | −0.81 ± 0.78 | ||
| Pos | 7 | 909 ± 50** | 27.3 ± 14* | 19 ± 10 | −0.55 ± 0.59 | 66.2 ± 3.7* | 54.3 ± 18.8 | 10.8 ± 4 | 0.34 ± 0.74 | ||
| All | Pre | 15 | 888 ± 156** | 38.1 ± 23.3* | 27 ± 16.5* | −0.3 ± 1.26** | 69.4 ± 11.6** | 61.2 ± 35.2 | 10.8 ± 4.7 | 0.49 ± 1.39* | |
| N2 | 15 | 914 ± 188** | 44 ± 31.7 | 31.2 ± 22.5 | −0.03 ± 1.64** | 68.6 ± 15.9** | 69.2 ± 43.8 | 12.1 ± 10.4 | 0.67 ± 2.59** | ||
| Pos | 15 | 802 ± 127**A | 21.1 ± 13.5* | 15 ± 9.6* | −1.2 ± 0.92*A | 76.7 ± 12.9**B | 42 ± 21.1 | 15.4 ± 7.2* | 1.73 ± 1.83**A | ||
mMissing data due to lack of sleep or ECG artifacts. Data as mean ± SD. *p <0.05, **p <0.001 comparing the same phase with NN. A p <0.05, B p <0.001 comparing with pre in the same condition (Linear Mixed Model).