Fig. 4.

Relationship of mouth status and parameters of nocturnal water loss. Nocturnal difference of hematocrit (A), hemoglobin levels (B) and estimated plasma volume (C) across subjects with different extent of mouth opening, which were observed via a day & night infrared camera during polysomnography. p values for trend = 0.062, 0.031, 0.042, respectively. MO ≥ 50%: time spent with mouth open ≥50% of total sleep time, MO<50%: time spent with mouth open <50% of total sleep time, MC: mouth closed (vs MC: ∗p < 0.05, ∗∗<0.005; MO ≥ 50% vs MO<50%: p < 0.05, Mann–Whitney U test).