Background: Few studies have assessed impact of sleep related physiological events on arousals. Methods: Overnight PSG recording of 30 healthy volunteers were analysed for occurrence of various sleep events and arousals during light sleep. Results: 864 arousals (N1=210; N2=654) were noted during light sleep in 30 patients. Forty-three arousals were de novo (N1=18; N2=25). The mean arousal per patient was 28.8±16.3 (median: 24; range: 9-84). In N1, sleep events associated with arousals included PLM- 157 (74.8%); roving eye movements- 92 (43.8%); vertex transients- 45 (21.4%); desaturation- 5 (2.4%); snore- 9 (4.3%); and apnea- 3 (1.3%). In N2, sleep events associated with arousals included sleep spindle- 570 (87.2%); PLM- 441 (67.4%); K complex- 226 (34.6%); snore - 85 (13%); vertex sharp transients- 57 (8.7%); desaturation - 5 (0.8%); and apnea - 28 (4.3%). The number of arousals in N1 and N2 that occurred de novo, and with single and multiple events were: a) N1 - de novo 18 (8.6%); Single event - 91 (43.3%) and multiple events – 101 (48.1%); b) N2: de novo – 25 (3.8%); single event - 129 (19.7%) and multiple event – 500 (76.5%). Conclusions: In light sleep, 95.02% arousals were associated with physiological events viz. PLM, roving eye movements, and vertex sharp transients in N1 and sleep spindle, PLM, and K complexes in N2. Comparative studies in health and disease may enhance the understanding of arousal mechanisms.