Table 1 Characteristics of studies included

Barling, NR and Raine, SJ (2005) [41]

60 healthy volunteers (14 males, 46 females)

Mean age 41.5 (range 17–63)

No information about further demographic data in the sample

RCT

Three experimental groups,

one control group

Two sample points:

• pre-test before the intervention

• post-test after three weeks of self-practice

1) PMR

2) PMR + guided imagery (GI)

3) PMR + GI + deep trance (DT) with specific mind-body healing language

Tape with recorded intervention for self-practice

No intervention

Burnout Assessment Test (BAT) [60]

Depression Anxiety Stress Scales (DASS) [61]

Saliva Immunoglobulin A (sIGA) by “sucking in their mouth”

• Significant condition effect for change in burnout (F(3, 14) = 8.46, p > 0.001), depression (F(3, 14) = 5.13, p > 0.003), anxiety (F(3, 14) = 6.62, p > 0.001) and stress (F(3, 14) = 4.02, p > 0.01);

• Significant differences in changes in burnout, anxiety, and depression between the control group and the DT group (no p-score reported)

+

One-way analysis of variance (ANOVA)

Multiple regression analyses

-

Small sample size

No information about further demographic data and health-related behaviors in the sample

No information about way of random assignment to the experimental groups

No information about results of post hoc-comparisons between groups

Cardena et al. (2013) [42]

56 healthy volunteers

10 males, 46 females

Mean Age 31.13 (SD = 10.00; range 20–61)

44 students, 11 worked, 1 unemployed

21 participants dropped out

RCT

One experimental group

One control group

Three times of measurement:

1. before the hypnotic intervention

2. after two weeks after the hypnotic intervention for group 1

3. after further two weeks after the hypnotic intervention for group 2

Hypnotic intervention: participants were asked to listen to a recording (length 23 min) at least once a day for 14 days.

The tape script consists of an general induction with a focus on breathing, counting a deepening procedure; imagining of specific place of security, peace, and control; creating a personalized “anchor”, posthypnotic suggestions

Waiting list control group

Perceived Stress Scale (PSS) [53]

Shirom-Melamed Burnout Questionnaire (SMBQ) [62]

Ways of Coping Questionnaire (WCQ) [63]

General Health Questionnaire 12 (GHQ-12) [64]

• Less stress (t(33) = -2.751, p < .01) and better overall health (t(22.5) = -3.159, p < .004) in hypnosis than in control group

+

precise information about exclusion criteria and way of randomization

ANOVAs

-

Many drop-outs

Gruzelier et al. (2001) [43]

28 volunteer pre-clinical medical students

17 males, 11 females

Mean age 20.1

RCT

one experimental group

one control group

Two sample points

• Baseline: four weeks before examination

• Exam: during the exam period

Group hypnosis three weeks before examinations

Tape with recorded intervention for self-practice

Hypnotic induction: visual fixation, relaxation and deepening exercises, instructions aimed at improving immune function and to mobilise resources by increasing alertness, energy and concentration (length 20 min)

No intervention

Lymphocyte counts (CD3, CD4, CD8, CD 8/4%, CD 19, NKC)

Cortisol

Life style questionnaire

Emotional state: scales of tension, calmness, energy and tiredness) [65]

State anxiety scale [66]

Activated and withdrawn personality scales [67]

• Immunological measures: reduction in NK cells with exam stress in controls, non-significant increase with hypnosis (F(2, 25) = 6.03, p < .007);

• Mood: no group differences in mood changes (no F- and p-scores reported);

• ratings of energy higher at exam time in hypnosis than in control group (F(1, 26) = 6.16, p < .01)

-

Small sample size

Some results not reaching significance are reported and interpreted as positive results

Kiecolt-Glaser JK et al. (1986) [44]

34 first-year medical students

22 male, 12 female

Mean age 23.5

RCT

One experimental group

One control group

Two sample points:

1. one month before examination

2. on the day of examinations

Hypnotic/relaxation group during lunch hours; 5–10 sessions in 2.5 weeks before the second blood draw

First hypnotic session: overview of hypnosis, group induction;

Each subsequent session: series of deepening exercises used in the initial session, self-hypnosis, progressive relaxation, autogenic training, various imagery exercises, suggestions for greater relaxation throughout the day and enhanced comprehension and retention of academic material (Sessions lasted 25–40 min);

Written manual that specified the content and order of components within each the sessions and request for daily practice

No intervention

Brief Symptom Inventory (BSI) [54]: changes in global stress

State Loneliness Scale [68]

Assessment of the degree of relaxation achieved during each session (self-rating 1–9)

Academic performance

Immunological data

Percentage of helper/inducer cells

Percentage of suppressor/cytotoxic cells

Helper/suppressor-cell ratio

NK activity

Nutritional data: Albumin, TIBC, Transferrin

• BSI: significant increases in anxiety (p < .01), obsessive-compulsive symptomatology (p < .05) and in the global severity index (p < .05) only in no-intervention group

No main effect for group and no group x time interaction in

• Loneliness

• Changes in health-related behaviors

• Academic performance

• Immunological data

• Nutritional data

+

Repeated-measures analyses of variance design

multiple regression analyses

-

Small sample size

Kiecolt-Glaser JK et al. (2001) [45]

34 students who obtained a score of 7 or higher on both scales (HGSHS-A and SHSS-C) among 130 students volunteered for the initial screening session

14 male, 19 female

Mean age 23.48 (SD +/− 1.97)

RCT

One experimental group

One control group

Two sample points:

1. within the first few days of the quarter

2. three days before the first major academic examination of the term

5–10 sessions during lunch hours that began 8 days before the second blood draw

First hypnotic session: overview of hypnosis, group induction;

Each subsequent session: series of deepening exercises used in the initial session, various imagery exercises, suggestions for greater relaxation throughout the day and enhanced comprehension and retention of academic material (sessions lasted 25–40 min);

Written manual that specified the content and order of components within each the sessions and request for daily practice

No intervention

Self-rating of anxiety (0–10) prior to each of the group inductions

Current relaxation after completion of group induction

Perceived Stress Scale [53]

Positive and negative Affect Schedule PANAS [69]

New York University Loneliness Scale [70]

Immunological Assays

Blastogenic response to phytohemagglutinin (PHA); blastogenic response to concanavalin A (Con A); T-lymphocytes, NK cells, macrophage/monocytes, IL-1β

No significant group x time interaction, no group effect for

• Stress (PSS) and negative affect (PANAS)

• Loneliness

• Immunological data: stable values for PHA stimulation (F(1, 31) = 4.94, p < .04), Con A concentrations (F(1, 31) = 4.26, p < .05), for CD3 + T-lymphocytes (F(1,31) = 5.76, p < .03)- and CD4+ T-lymphocytes (F(1, 31) = 6.05, p < .03) in hypnosis and declines for control group; no significant group effects or group x time interaction for CD8 + −, NK-cells and IL-1β

-

Small sample size

Naito A et al. (2003) [46]

48 students (39/48 medical students);

22 males, 26 females;

Age range 19–23 years with one participant of 37 years

Participants were paid £30 at the end of the study.

Prospective randomized controlled trial

Three groups

• Stress reduction training with self-hypnosis

• Johrei

• Mock neurofeedback relaxation control

Two sample points:

• Baseline: before training

• Exam: 1–2 months later as exams approached

4 Weekly sessions during a 1-month intervention period

Self-hypnosis training: subjects learnt a Spiegel-type eye-roll for instant relaxation first and then a slower relaxation-type induction; subjects were taught a basic immune imagery, and two anxiety management techniques;

standard tape-recording using a relaxation induction and imagery description and request for self-hypnosis three times a day

Johrei healing method: introduction to Johrei philosophy and the coreprinciples needed such as healing oneself by healing others; the subjects were requested to practice Johrei daily with a partner; the practitioner imagines light entering his body being concentrated through his hands towards the recipient and moves his hands slowly from head down to kidney area without touching the recipient

8 mock neurofeedback sessions over 1 month

Self-reported stress [53]

Personalised Emotional Index: practice and mood data

Peripheral blood lymphocytes: CD4+ T cells, CD8+ T cells, CD56+ Natural Killer cell percentages (NK cells) and NK cell cytotoxic activity

Natural Killer cells: increase only in Johrei, no change in hypnosis and relaxation (F(1,33) = 5.86, p = .007)

CD8+ T cells: the extent of increase significant greater in hypnosis than in relaxation, but not than in Johrei (F(1,33) = 3.02, p = .063).

CD4+ T cells: decline only in Johrei, no change in hypnosis and relaxation (F(2, 32) = 4.71, p = .016)

+

Repeated-measures ANOVA followed by paired comparisons with non-parametric tests

-

Small sample size

No information about health-related behaviors in the sample

Due to very small samples it is impossible to draw reliable conclusions of results of ANOVA with three factors

Stanton HE (1989) [47]

40 high school teachers

No information about further demographic data in the sample

Prospective randomized controlled trial

One experimental group

One control group

Three sample points:

• Before treatment

• Immediately after treatment

• 12 months after treatment

4 weekly sessions involving a hypnotic induction and 10 positive suggestions derived from key elements of Rational-Emotive Therapy based on a reformulation of Ellis’s challenges to his clients’ irrational ideas (Ellis and Grieger, 1977)

• 1. Session (1 h): hypnotic training and introduction to the 10 suggestions

• 2.-4. Session (0.5 h): standardized induction (breath, counting, body relaxation, pleasant scene imagery) and five repetitions of the suggestions

4 weekly sessions with discussingstress reduction methods

Face Valid Stress Test

Level of reasonable thinking: Teacher Idea Inventory [71]

• Teacher Idea Inventory: significant less irrational thinking in hypnosis than in control group after treatment (F(1, 19) = 32.61, p < .01) and at 12-month follow-up (F(1, 19) = 30.65, p < .01).

• Face Valid Stress Test: significant lower stress level in hypnosis than in control group

at 12-month follow-up (t(19) = 5.08, p < .001)

+

Repeated-measures ANOVA followed by paired comparisons with non-parametric tests

-

Stanton HE (1991) [48]

30 secretaries from a large business firm

Age range 27–43

RCT

One experimental

one control group

Three sample points:

• Before treatment

• Immediately after treatment

• 2 months after treatment

Two sessions (1. 50 min, 2. 25 min) while participants listened to an standardized tape which guided them through five stress-reduction steps:

• physical relaxations induced by concentration upon the breath

• mental calmness induced by imagining the mind as a pond into which one can drop concepts such as calmness, confidence as stones

• disposing of “rubbish” as fears, doubts, and worries down a chute

• removal of a barrier of self-destructive thoughts, fears of failure

• enjoyment of a special place and remake the day

Two sessions of the same duration discussing stress management procedures

(stage 1)

After the 2 months follow-up of the experimental group the control group experienced the same two treatment sessions (stage 2)

Stress thermometer [72]

Anecdotal reports

• Significantly greater stress reduction in hypnosis than in control group immediately after the treatment (Scheffé F(14) = 3.64, p < .01) and at 2-month follow-up (Scheffé F(14) = 3.47, p < .01)

+

Repeated measures ANOVA

-

Small sample size

No standardized, validated self-report measures

Whitehouse et al. (1996) [49]

35 first-year medical students

14 male, 21 female

Mean age 24.8

Prospective randomized controlled trial

One experimental group

One control group

Four sampling points:

• Orientation

• Late semester

• Exam stressor,

• Recovery

19-week investigation

Self-hypnosis training condition (n = 21)

14 sessions à 90 min around the noon hour, one day per week

request for self-hypnosis exercises at least 15 min each day.

No treatment

Subjects filled out the same daily diaries

Psychosocial data

Profile of Mood States [73]

Brief Symptom Inventory (BSI) [54]

UCLA Loneliness Scale [74]

Immunologic data

• T, B, monocyte, granulocyte, NK, T4, T8, helper-inducer, and suppressor-inducer cells

• Mitogen-induced lymphocyte stimulation by ConA, PHA and PWM

• BSI: significant less anxiety to exam period in hypnosis than in control group (F(3, 96) = 2.96, p < .05)

No between group differences

• UCLA loneliness scale

• Immunologic data

+

Immunological data: repeated-measures multivariate analyses of variance (MANOVAs)

Psychosocial data: univariate repeated-measures ANOVAs