Sugar interferes with relaxation

In a controlled experiment, a team of neuroscientists led by Professor Jens Prüssner studied the condition of 94 healthy adult volunteers. The participants, who were fasting, were randomly assigned to groups: some consumed a glucose drink, while others drank plain water. Afterward, some volunteers received a relaxing massage, while others simply rested. Scientists continuously monitored cardiac activity, measuring heart rate variability to assess the activity of the parasympathetic system and the pre-ejection period (a measure of cardiac contractility used in non-invasive studies) to monitor the sympathetic nervous system.

The results showed that subjective perceptions of rest do not always correspond to the actual state of the body. All participants in the study, regardless of whether they drank water or a sugary beverage, reported feelings of psychological relaxation after receiving a massage or during a resting phase. The devices confirmed that in all cases, the parasympathetic nervous system, which is responsible for slowing down rhythms and restoring resources, was activated. However, in those who consumed sugar, the sympathetic nervous system, which maintains the body in a state of latent arousal, remained highly active.

Dr. Maria Mayer explains that this biological mechanism effectively blocks full relaxation. The sympathetic system, which is activated by glucose, continues to function in a state of readiness for stress, even when the individual feels emotionally calm. Thus, sugar prevents the natural slowing down of physiological processes, which is necessary to achieve the maximum effect of relaxation. Scientists have concluded that in order to get a full result from practices such as meditation or progressive muscle relaxation, you should not consume foods with a high sugar content immediately before the session.

This work also highlights the importance of a comprehensive analysis of the autonomic nervous system in medical research. If scientists had limited themselves to studying only the parasympathetic division, they would not have noticed the negative effect of sugar on the body’s overall ability to transition to a state of rest. The study proves that eating habits directly affect the effectiveness of stress management techniques, and recommends taking into account metabolic factors when planning recovery procedures. This is especially important for people who want to minimize the effects of chronic fatigue and improve the quality of their physiological rest.