Eur Arch Psychiatry Clin Neurosci (2011) 261:341–347 Table 3 Demographics of patients with 4 day hypomanic episodes compared to additional patients with 3, 2, and 1 day hypomanic episodes Additional DF patients (N = 43) 4 day hypomanic 3 day hypomanic episode 2 day hypomanic episode 1 day hypomanic episode episode Patients P P P (N = 102) Additional DF patients (N = 88) Additional DF patients (N = 169) 40.4 (9.0) 20.1 (10.3) 20.0 (10.8) 2.5 (3.1) 103.1 0.400 39.5 (11.0) 187.1 0.687 39.8 (11.3) 204.9 0.524 79.9 0.068 20.6 (10.9) 169.2 0.054 21.4 (10.7) 188.7 0.102 73.1 0.032 19.0 (12.2) 158.4 0.050 18.4 (12.6) 221.1 0.054 120.4 0.548 1.8 (2.5) 137.2 0.079 1.9 (2.8) 125.1 0.075 2 0.279 1 0.650 1 0.925 Agea (mean years, SD) Age of onseta (mean years, SD) Years of illnessa (mean years, SD) Hospitalizationsa (mean N, SD) Diagnosisb Bipolar I (N, %) Bipolar II (N, %) Genderb Female (N, %) Male (N, %) Education levelb High school (N, %) Some college (N, %) College graduate (N, %) Employment statusb Disabled (N, %) Working full-time (N, %) Other (N, %) Marital statusb Married (N, %) Single (N, %) Divorced (N, %) Number of daily medicationsa (mean N, SD) Taking any mood stabilizerb (N, %) Taking lithiumb (N, %) Taking valproateb (N, %) Taking lamotrigineb (N, %) Taking antidepressantb (N, %) Taking antipsychoticb (N, %) Taking benzodiazepineb (N, %) Taking sleep medicationb (N, %) 38.9 (11.9) 23.8 (11.3) 15.5 (10.7) 2.8 (5.0) 64 (63) 38 (37) 71 (70) 31 (30) 13 (14) 35 (38) 45 (48) 21 (24) 51 (59) 15 (17) 45 (48) 34 (37) 14 (15) 2.8 (1.6) 80 (78) 30 (29) 24 (24) 34 (33) 50 (49) 54 (53) 27 (27) 10 (10) 31 (72) 12 (28) 27 (63) 16 (37) 3 (8) 15 (37) 22 (55) 11 (28) 17 (42) 12 (30) 20 (50) 15 (37) 5 (13) 2.7 (1.4) 36 (84) 11 (26) 11 (26) 14 (33) 23 (54) 17 (40) 11 (26) 3 (7) 1 2 2 2 1 1 1 1 1 1 1 1 345 0.570 0.423 0.103 0.927 0.959 0.295 0.507 0.451 0.766 0.026 0.274 0.104 a Student’s t test, equal variances not assumed b Pearson Chi-Square test results were very similar to our prior ﬁndings, with the current sample about double in size [4]. The majority of symptomatic days occurred outside of a DSM-IV episode, which agrees with prior longitudinal studies of bipolar disorder [16–18]. With a 4-day minimum length, more than half of the days of hypomania occurred outside of an episode. Even with a 2-day minimum length, one-third of all hypomania remained outside of an episode. Single days of hypomania were so frequent that with a length criterion of 1-day, 271 patients (69%) experienced an episode. For any episode length, the percent of hypomanic days occurring outside of an episode did not differ between bipolar I and II disorder. Additionally, about 60% of the reported days of depression occurred outside of an episode regardless of the length criterion for hypomania. In prior research based on clinician interviews, and including patients with depressive disorders, most hypo- mania lasted for 1–3 days [1, 2, 8, 9, 19], which is con- sistent with the current ﬁndings. The high frequency of brief hypomania in this sample suggests that if the length criterion for an episode of hypomania is decreased, the frequency criterion should be increased, as frequency may 123 1 2 2 2 1 1 1 1 1 1 1 1 0.423 0.544 0.169 0.928 0.467 0.640 0.792 0.928 0.623 0.140 0.911 0.586 58 (66) 30 (34) 59 (67) 29 (33) 9 (11) 29 (35) 44 (54) 20 (25) 33 (41) 27 (34) 36 (46) 30 (38) 13 (16) 2.6 (1.6) 69 (78) 20 (23) 20 (23) 29 (33) 44 (50) 33 (38) 20 (23) 5 (6) 1 2 2 2 1 1 1 1 1 1 1 1 0.705 0.736 0.030 0.928 107 (63) 62 (37) 112 (66) 57 (34) 18 (11) 51 (32) 91 (57) 37 (23) 75 (48) 46 (29) 78 (49) 59 (37) 21 (13) 2.6 (1.5) 0.997 133 (79) 0.297 40 (24) 0.896 34 (20) 0.956 64 (38) 0.893 86 (51) 0.033 66 (39) 0.551 35 (21) 0.293 8 (5) 86.8 0.769 184.7 0.310 206.3 0.183