By John M. de Castro, Ph.D.
“A simple meditation for sleep . . . is to focus on the breath while lying in bed as you are preparing to go to sleep. Follow the breath moving into and out of the body. As you are being aware of the breath just allow yourself to sink into the bed with each breath. . . . By taking this mindful attitude, sleep is facilitated by simply being aware of the moment-to-moment experience of relaxing into the bed, without judging or being critical of that experience, so that the mind can gently slip into sleep.” – John Cline
We spend about a third of our lives in sleep, but, we know very little about it. It is known that sleep is not a unitary phenomenon. Rather, it involves several different states that can be characterized by differences in physiological activation, neural activity, and subjective experiences. In the waking state the nervous system shows EEG activity that is termed low voltage fast activity. The electrical activity recorded from the scalp is rapidly changing but only with very small size waves. When we close our eyes and relax the heart rate and blood pressure decline and muscles relax. In this state the EEG shows a characteristic waveform known as the alpha rhythm, which is a large change in voltage recorded that oscillates at a rate of 8 to 12 cycles per second. Subjectively, the mind slows down and often day dreaming occurs.
When sleep first occurs, the individual enters into a stage called slow-wave sleep, sometimes called non-REM sleep. The heart rate and blood pressure decline even further and the muscles become very soft and relaxed. In this state the EEG shows a characteristic waveform known as the theta rhythm, which is a large change in voltage recorded that oscillates at a rate of 4 to 8 cycles per second. Subjectively, the mind enters into a state of slow and distorted experiences. It is here that nightmares can occur. As the individual goes even deeper into sleep something remarkable happens as the individual enters into rapid eye movement sleep (REM sleep). Here the muscles become extremely inhibited and flaccid, but the eyes move rapidly under the closed eyelids as if the individual was looking around. At the same time the heart rate and blood pressure increase and become very variable and sometimes very high. Subjectively this is where elaborate dreams occur.
It has been shown that mindfulness training, including meditation practice, affects sleep and tends to improve sleep and reduce insomnia. In today’s Research News article “Short Meditation Trainings Enhance Non-REM Sleep Low-Frequency Oscillations”
Or see below or see full text at:
http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0148961
Dentico and colleagues investigate the effects of long-term meditation on the electrical activity of the brain (EEG) during sleep. They recorded the EEG during sleep before and after 2-days of intensive meditation. They found that after meditation, the EEG activity over the frontal and parietal cortical areas increased in power in the alpha and theta rhythm range of 1-12 cycles per second (Hertz). The more experience that the participants had with meditation the larger the increase in the EEG power during sleep following the meditation. These results suggest that long-term meditation practice changes the nervous system making it more sensitive to the effects of meditation on sleep.
Other research has demonstrated that long-term meditation practice produces increases in the size, activity, and connectivity of the frontal and parietal regions. So, the finding that EEG power increases during sleep in these areas as a result of long-term meditation makes sense. It is not known, however, exactly what the increased EEG power indicates. But, it can be speculated that is may indicate deeper sleep in non-REM, slow-wave, sleep. Perhaps enhancing subjective experiences during this phase of sleep. This would fit with the improvements in sleep seen in meditators. It remains for future research to test these speculations and determine exactly what meditation does to the sleeping brain and the subjective experiences of the dreamer.
Regardless of the merits of this speculation, it is clear that meditation alters the sleeping brain.
“there are whole-health benefits to the practice of mindfulness, wherein every aspect of health stands to gain. A healthier you is likely to sleep better, and a better-sleeping you is likely to be healthier.” – Michael Breus
CMCS – Center for Mindfulness and Contemplative Studies
Study Summary
Dentico D, Ferrarelli F, Riedner BA, Smith R, Zennig C, Lutz A, et al. (2016) Short Meditation Trainings Enhance Non-REM Sleep Low-Frequency Oscillations. PLoS ONE 11(2): e0148961. doi:10.1371/journal.pone.0148961
Abstract
STUDY OBJECTIVES: We have recently shown higher parietal-occipital EEG gamma activity during sleep in long-term meditators compared to meditation-naive individuals. This gamma increase was specific for NREM sleep, was present throughout the entire night and correlated with meditation expertise, thus suggesting underlying long-lasting neuroplastic changes induced through prolonged training. The aim of this study was to explore the neuroplastic changes acutely induced by 2 intensive days of different meditation practices in the same group of practitioners. We also repeated baseline recordings in a meditation-naive cohort to account for time effects on sleep EEG activity.
DESIGN: High-density EEG recordings of human brain activity were acquired over the course of whole sleep nights following intervention.
SETTING: Sound-attenuated sleep research room.
PATIENTS OR PARTICIPANTS: Twenty-four long-term meditators and twenty-four meditation-naïve controls.
INTERVENTIONS: Two 8-h sessions of either a mindfulness-based meditation or a form of meditation designed to cultivate compassion and loving kindness, hereafter referred to as compassion meditation.
MEASUREMENTS AND RESULTS: We found an increase in EEG low-frequency oscillatory activities (1-12 Hz, centered around 7-8 Hz) over prefrontal and left parietal electrodes across whole night NREM cycles. This power increase peaked early in the night and extended during the third cycle to high-frequencies up to the gamma range (25-40 Hz). There was no difference in sleep EEG activity between meditation styles in long-term meditators nor in the meditation naïve group across different time points. Furthermore, the prefrontal-parietal changes were dependent on meditation life experience.
CONCLUSIONS: This low-frequency prefrontal-parietal activation likely reflects acute, meditation-related plastic changes occurring during wakefulness, and may underlie a top-down regulation from frontal and anterior parietal areas to the posterior parietal and occipital regions showing chronic, long-lasting plastic changes in long-term meditators.