Figure 6

We included 20 studies with a total of 34 comparisons in the meta-analysis. Some of the studies reported data from more than one group: REM-sleep^{1, 6}; non-REM sleep^{3, 5}; positional obstructive sleep apnea (OSA)^{2, 4, 18}; non-positional OSA^{7, 8}; with tonsillo-andenomegaly⁹; with adenoid hypertrophy¹⁷; no obstruction¹⁵; at 40-44 weeks post-conseptional age¹⁶; at 45-49 weeks post-conseptional age¹⁴; at 50-54 weeks post-conseptional age¹⁰; at 55-59 weeks post-conseptional age¹²; left lateral vs. supine position¹¹; right lateral vs. supine position¹³; preoperative night¹⁸, first¹⁹ and third²⁰ postoperative night.