Author, year, country

Source population periods of recruitment/data collection

Total number of eligible subjects (n)

Response rate (%)

Outcomes of interest

Key findings

Hirata, et al. (2017)

Brazil

Medical students, 19 - 30 y.o. (mean age = 22.1 ± 2.1), in their first to fourth semester of the medical course at Federal University of Ceará, Brazil, during a 4-month period

n = 161

Participation rate 97%

Females 52.2%

Depressive symptoms (BDI: score range 0 - 63, >10 indicates depressive symptoms).

Exposure measurement: Home-Ostberg morning/eveningnesss self-report questionnaire (MEQ), score range 16 - 86)

classification of types into:

· Definitely evening (26 - 30)

· Moderately evening (31 - 41)

· Indifferent (42 - 58)

· Moderately morning (59 - 69)

· Definitely morning (70 - 86)

The MEQ scores were inversely correlated to the BDI scores (p = 0.005)

Odds of depressive symptoms in students with:

(a) Evening-type preference (definitely and moderately evening): OR = 0.66 (95% CI 0.05, 0.88)

(b) Evening-type preference after controlling for controlling for family history of depression: OR = 0.69 (95% CI 0.52 - 0.93)

(c) Evening-type preference after controlling for physical activity: OR = 0.66 (95% CI 0.49 - 0.89)

(d) Evening-type preference after controlling for family history of depression and physical activity: OR = 0.71 (95% CI 0.52 - 0.95)

Hsu et al. (2012)

First-year undergraduate students (mean age = 19.4 y.o.) attending the National Taiwan University, completed self-administered questionnaires at school in September 2002.

n = 2919

Participation rate 79.2%

Females = 51.5%

Depression and anxiety symptoms (BSRS domains): Items scored from 0 (not at all) to 4 (extremely), with higher scores reflecting degrees of discomfort in past week.

Exposure measurement = M-E Scale (MES): score ranging from 13 to 55, with higher scores suggesting

Association between Chronotype and depression score in males (F = 6.32, p < 0.01):

E vs I: Cohen’s d^#= 0.33

E vs M: Cohen’s d^# = 0.55

I vs M: Cohen’s d^# = 0.22

Association between Chronotype and depression score in females (F = 13.89, p < 0.001):

morningness tendency:

Eveningness (E)

Intermediate (I)

Morningness (M)

E vs I: Cohen’s d^# =0.39

E vs M: Cohen’s d^# = 0.43

I vs M: Cohen’s d^# = 0.04

Association between Chronotype and anxiety score in males (F = 3.9a2, p ≤ 0.05)

E vs I: Cohen’s d^# =0.31

E vs M: Cohen’s d^# = 0.49

I vs M: Cohen’s d^# = 0.18

Prat et al. (2013)

Spain

Undergraduate students 17 - 30 y.o. (mean age = 21.4), completed questionnaires while attending a psychology course at the University of Barcelona

n = 517

Response rate = 93.5%

Females 66.5%

Psychological symptoms (GHQ-28): incorporates 4 subscales (psychosomatic symptoms, anxiety and insomnia, social dysfunction, and severe depression).

Exposure measurement = Spanish version of the CSM: categories based on scores indicating evening-type (£25), neither-type (26 - 36), Morning-type (³37).

Association between circadian typology (evening-,morning-, neither-type) and total GHQ-28 score: F =11.02, p ≤ 0.001, partial n² = 0.041

Association between circadian typology (evening-,morning-, neither-type) and insomnia score: F = 7.74, p ≤ 0.001, partial n² = 0.029

Association between circadian typology (evening-,morning-, neither-type) and severe depression: F = 3.22, p ≤ 0.05, partial n² = 0.029