Sleep, alertness and quality of life

Train drivers from Stockholm who started relaxation because of occupational stress were randomly assigned to learn either Acem Meditation or a muscle relaxation technique known as progressive relaxation. After six months, both groups reported better sleep and quality of life, as well as reduced psychological tension. They also had less harmful concentrations of cholesterol and triglycerides in the blood, especially the meditation group. Blood pressure was reduced in the meditation group only. Drivers in the progressive relaxation group felt more energetic, whereas participants in the meditation group felt more relaxed and rested. There were no changes in the control group.

Several studies show that people working irregular hours and night shifts experience problems with sleep and alertness. In a survey on the working environment of train drivers in Stockholm in 1988, 80% reported some form of sleep disturbance, e.g. difficulty falling asleep and sleep deficit. These disturbances affected the drivers’ leisure-time quality of life. They described some of their problems as “walking in a haze”, “feeling like a zombie,” and “lack of energy”. The aim of our study was to find methods the drivers could use to reduce problems related to shift working, thereby improving their health and quality of life. Eighty train drivers participated in the study. Twenty of them learned Acem Meditation, 20 learned progressive relaxation, and 40 were included in a control group who did not practise a relaxation technique.

Before the study and at the end of it six months later, blood pressure, cholesterol and triglycerides were measured by medical examination. Changes in health-related quality of life and lifestyle factors such as diet, exercise, smoking and use of alcohol were assessed by standardised questionnaires.

Different relaxation techniques

The two relaxation methods partly differ in their means and goals for relaxation. Progressive relaxation is a goal-oriented, directed technique, whereas Acem Meditation is a process-oriented, nondirected technique.

During progressive relaxation, directive action is used to achieve a specific goal. This takes place by systematically contracting and then relaxing body muscles, following guidance from an instructor or an audio recording. Thoughts and feelings that spontaneously come to mind are considered disturbances to be excluded, in the same way as when we try to concentrate on reading something in a book. Progressive relaxation is therefore classified as a concentration technique.

During Acem Meditation, a meditation sound is used to create optimal conditions for spontaneous thoughts and feelings to pass freely through the mind. From time to time, the person meditating will spontaneously be absorbed in thoughts and other experiences. Such absorption in thoughts is part of the process in Acem Meditation, which is a nondirected technique. When it happens, the meditator simply starts repeating the meditation sound again.

In progressive relaxation, muscular tone is reduced through volitional influence. In Acem Meditation, relaxation results from a reflex that is triggered without direct muscle action.

In the present study, the aim was for drivers in the progressive relaxation group to use an audio cassette with instructions for 20 minutes twice daily. Those in the Acem Meditation group should meditate for 30 minutes twice daily. Both groups participated in a standard eight-week beginner’s course in the relevant technique. At group meetings, participants discussed their experiences and boosted one another’s motivation to practise the technique regularly during the study.

Blood pressure and cholesterol

At the beginning of the study, blood pressure was within normal limits in all three groups. At termination, however, the Acem Meditation group differed from the other groups by showing a reduction in mean diastolic blood pressure from 82 mm Hg to 78 mm Hg (table 1). This difference was statistically significant when the meditation group was compared to the progressive relaxation and control groups combined (p<0.05). Systolic blood pressure was significantly reduced within the Acem Meditation group. Similar results have been reported in recent studies of patients with high blood pressure. These are discussed in more detail in Ellingsen & Holen’s contribution to the present volume.

There were also less harmful concentrations of cholesterol and triglycerides. At the beginning, triglyceride concentrations were substantially higher in both the progressive relaxation group and the Acem Meditation group compared to the controls (table 2). This may reflect the fact that the progressive relaxation group and the Acem Meditation group were recruited among train drivers whose

Table 1 – Blood pressure

1 One-way analysis of variance (ANOVA). P<0.05 indicates statistically significant change, i.e. not likely to be caused by chance.

2 p<0.05 if compared to the progressive relaxation and control groups combined.

Table 2 – Cholesterol and triglycerides

1 One-way analysis of variance (ANOVA). P<0.05 indicates statistically significant change, i.e. not likely to be caused by chance.

level of stress was higher than the control group at the outset. At termination of the study, triglyceride concentrations were comparable between the Acem Meditation group and the controls, and had also decreased in the progressive relaxation group, perhaps indicating that the two techniques contributed to normalisation of stress levels.

Cholesterol is regarded as harmful when found in lowdensity lipoproteins (LDL) and beneficial when found in high-density lipoproteins (HDL). A useful overall method to evaluate health risks related to cholesterol is to calculate the ratio between LDL and HDL cholesterol. In the present study, the LDL/HDL cholesterol ratio decreased in all three groups, especially in the Acem Meditation group. There was a clear relationship between individual changes in blood lipids and levels of physical activity. Participants who increased their level of exercise during the study achieved the largest reductions in LDL/HDL cholesterol ratio.

Sleep, quality of life and psychological tension

Indexes for sleep and quality of life increased in both relaxation groups. At the same time, indexes in the control group either remained unchanged or decreased. The changes were small, but indicate that the relaxation techniques positively influenced sleep and quality of life in the long run.

Summary indexes for psychological tension started at a higher level in the two relaxation groups than in the control group. Both relaxation groups achieved decreases and ended up at the same levels as the control group (table 3). The decrease was largest in the Acem Meditation group, which also started at the highest level. The results were in accordance with the train drivers’ statements about the effects they had achieved using the techniques.

Table 3 – Psychological tension

1 Summary index based on 59 questions, graded on a scale from 0 (best) to 4 (worst)

Subjective experiences

Participants in both relaxation groups reported noticeable changes in how they felt after practice. There was a slight difference between the two techniques. The drivers practising progressive relaxation felt more energetic, whereas those practising Acem Meditation felt more calm, relaxed and rested. Practising meditation or progressive relaxation during a break in their night shift instead of just sitting around made the drivers feel more energetic during the rest of the shift.

Conclusion

As discussed by Ellingsen & Holen in the present volume, results from this and other studies suggest that meditation practised with a free mental attitude is more effective in reducing blood pressure and psychological symptoms. The explanation may be that cultivating a free mental attitude enhances our capacity for mental processing, and that reduced psychological tension lowers blood pressure.

Study design and follow-up

The study was supported by the Swedish Occupational Health Fund (Arbetslivsfonden) and was initiated by Ingmari Hedlund, advisor at the Occupational Health Organization for Government Employees (Statshälsan/ Previa-Rikshälsan) in Stockholm. The other members of the project group were Lennart Axelsson, physician at the Swedish Railways (Statens Järnvägar), and Pär Westlund, Associate Professor at the Karolinska Institute.

The 40 participants who practised one of the techniques had volunteered to learn some form of relaxation. They were assigned to either method by drawing lots. This randomisation was stratified to ensure that the groups were as similar as possible with respect to age, gender and number of years they had worked in their present occupation. The induction period for both relaxation techniques was eight weeks. It was impossible to start teaching all 40 participants simultaneously due to their irregular working hours, so various groups started at different times to be able to meet on the same day eight weeks in a row. During the introductory period, participants were followed up once a week. Thereafter they were followed up once a month until the end of the six-month study. There was no other follow-up in addition to these scheduled meetings, but the participants could contact their instructor if they had questions.

In medical examinations before and after the study, blood pressure was recorded and blood samples were drawn for measurement of cholesterol and triglycerides. On two occasions approximately six months apart, all train drivers filled in the same questionnaire, including questions on rest, sleep, alertness, ability to concentrate and general health. Some questions were related to lifestyle factors such as diet, exercise, smoking and use of alcohol. Questions were selected from the well-documented Hopkins Symptom Check List 90, covering a wide range of areas such as headache, memory, appetite, pain, loneliness, sleep problems, etc. Participants indicated how much they experienced each symptom, and the answers were indexed on a scale from 0 to 4, where 0 represented the best value. A summary index for each person was calculated, and these summary indexes were compared among the groups. At conclusion of the study, participants also described in their own words the effects they had achieved from Acem Meditation or progressive relaxation.

The 40 participants in the control group were recruited among other train drivers in Stockholm who had not shown any interest in learning relaxation. They were matched to the other participants with respect to age, gender and number of years as train drivers, and were given medical examinations and filled in the same questionnaires at the same intervals as the drivers in the relaxation groups. The controls were not given any other follow-up.

At the final follow-up, 62% of the participants in the progressive relaxation group stated that they practised one to five times per week and 38% that they practised six to nine times per week. The corresponding figures in the Acem Meditation group were 63% and 37%, showing that compliance was comparable in the two groups. Sixteen of the 20 participants in the group for progressive relaxation, 19 of the 20 participants in the group for Acem Meditation, and 35 of the 40 participants in the control group completed the study. Even though participants practised the relaxation techniques less than recommended towards the end of the study, both physiological and psychological effects were recorded. This indicates that even a small effort is beneficial, although the effects presumably would have been even greater if participants had practised for the recommended time.