Table 2 Intervention characteristics of the included studies.

Babkoff 2002

BL and caffeine^a

DL and caffeine

EG: 6

CG: 6

2330–0230^c

1730–0830^f,h

0130–0430

Bjorvatn 2007

BL^b

Placebo capsules

EG: 17

CG: 17

0000–0500 and 1200–1430^c

0630–1830 and 1830–0630^g

Every 2 h from 2000 and so on

Bjorvatn 2020

BL

DL

EG: 35

CG: 35

0200–0300, 0300–0400, 0400–0500

2200–0600

every 2 h at 2200–0600

Boivin 2012

Intermittent BL^a

No

EG: 8

CG: 9

6 h from 2200, 2230, 2300, or 2330^c

8/8.5 h between 2200–0800^f

Every 2 h (phase shift) or every 30 min (sleepiness) at 0600–2200

Comtet 2019

BL

DL

EG: 18

CG: 18

0500–0530

2000–0800

0300, 0500, 0700, 0800

Dawson 1991

BL and DL^a

DL

EG: 6

CG: 7

2400–0400^c

2300–0700^f,h

0100, 0300, 0500, and 0700

Dawson 1995

BL^a

DL

EG: 8

CG: 8

2400–0400^c

2300–0700^f,h

At night

Griepentrog 2018

BL

SL

EG: 26

CG: 17

1900–0700

1900–0700

0500, 0700

Horowitz 2001

BL and fixed or free sleep

RL and fixed or free sleep

EG: 25

CG: 27

2300–0700

2300–0700, 0700–1100

2300–0700

Karchani 2011

BL^b

RL

EG: 45

CG: 45

2200, 2400, 0200 and 0400^c

0600–1400, 1400–2200, and 2200–0600 ^g

2300, 0100, 0300, and 0500

Kretschmer 2013

BL and RL^a

RL

EG: 16

CG: 16

2200–0200, 2300–0300, 0000–0400^c

2200–0400^f,h

Every 2 h/day

Babkoff 2002

E: 3000

C: 20–50

1

VAS and RIA

Sleepiness and phase shift

Bjorvatn 2007

E: 10,000

C: 0

8

KSS

Sleepiness

Bjorvatn 2020

E: 10,000

C: 100

3

KSS

Sleepiness

Boivin 2012

NA

7

VAS and RIA

Sleepiness and phase shift

Comtet 2019

E: 10,000

C: 8

1

KSS

Sleepiness

Dawson 1991

E: BL 6000 and DL 150–200

C: 150–200

3

Core temperature

Phase shift

Dawson 1995

E: 4000–7000

C: 50

3

RIA

Phase shift

Griepentrog 2018

E: 1500–2000

C: 300

1

SSS and ELISA

Sleepiness and phase shift

Horowitz 2001

E: 2500

C: 150

3

VAS and RIA

Sleepiness and phase shift

Karchani 2011

E: 2500–3000

C: 300

2

SSS

Sleepiness

Kretschmer 2013

E: BL 3000 and RL 300

C: 300

3

SSS

Sleepiness

Lee 2006

BL

DL

EG: 11

CG: 12

0045–0500

2300–0700

Every 30 min at 1530–1200; 0000–1800 in last day

Lee 2020

BL

DL

EG: 12

CG: 12

0100–0600

0100–0600

Every hour at 2100–0600

Lowden 2004

BL

RL

EG: 18

CG: 18

1515–2145, 2145–0630, or 2400–0630

1515–2145, 2145–0630, and 2400–0630

Every 2 h at 0000–0600, 0600–1400

Nagashima 2017

BL

DL

EG: 12

CG: 12

1000–1600

0000–0800

Every hour at 1800–0000

Sadeghniiat-Haghighi 2011

BL

RL

EG: 47

CG: 47

0030–0050, 0230–0250

0600–1800, 1800–0600^g

2200, 2400, 0200, 0400

Smith 2009

Intermittent BL pulse and RL

RL

EG: 9

CG: 10

0045–0400

2300–0700

Every 30 min/day

Sunde 2020

BL

SL

EG: 36

CG: 36

2300–0500

2300–0700

2330, 0100, 0230, 0400, 0530

Tanaka 2011

BL

No

EG: 61

CG: 61

0730–0800

0800–1700, and 1630–0830

1000, 1400

Thorne 2010

WL and wearing sunglasses

No

EG: 10

CG: 10

1300–1400

1800–0600, or 1900–0700

Every 4 h/day

Yoon 2002

BL

RL

EG: 12

CG: 12

0100–0500 and 0830–0930

2200–0800

4 times at 2400–0600

Lee 2006

E: 3500

C: < 50

2

RIA

Phase shift

Lee 2020

E: 430

C: < 1

1

KSS and RIA

Sleepiness and phase shift

Lowden 2004

E: 2500

C: 300

15

KSS and RIA

Sleepiness and phase shift

Nagashima 2017

E: > 3000

C: < 50

1

RIA

Phase shift

Sadeghniiat-Haghighi 2011

E: 2500

C: 300

1

SSS

Sleepiness

Smith 2009

E: 4100

C: < 50

8

RIA

Phase shift

Sunde 2020

E: 900

C: 90

3

KSS and ELISA

Sleepiness and phase shift

Tanaka 2011

E: 5444–8826

C: 0

30

KSS

Sleepiness

Thorne 2010

E: 3000

C: 0

4

RIA

Phase shift

Yoon 2002

E: NL 4000–6000 and SL 10,000

C: RL < 200 and SL 10,000

3

VAS

Sleepiness