To identify the relationship between sleep and cerebrospinal fluid ( csf) b-amyloid ( ab) and the key molecule involved in alzheimer disease i ( ad) pathogenesis, cognitively normal individual were instructed to wear an actigraph for 14 days to record total sleep time and time in bed. quantify of sleep was measured with total sleep time per 24 hours. sleep efficiency (%) is total sleep time divided by time in bed, cerebrospinal fluid was obtained by lumbar puncture to measure a b42. two independent sample t-test was used to compare those with high csf ab42 (> 500 pg/ml, group h) with those with a low csf ab42 level ( < 500 pg/ml, group l) ( results shown in the table below). which of the following statement(s) is/are correct interpretation (s) of the test results? select all that apply.