The brain in deep sleep and samadhi are remarkably similar. Both states have a calming effect on the body, reducing heart rate and breathing rate. While sleep provides a restorative alertness, meditation can provide an even deeper level of relaxation. This is because meditation can help to release the deepest ingrained impressions, or samskaras, from the system.
Research has shown that regular meditation can cause changes in the body that are similar to those that occur during sleep. This includes slowing heart rate, reduced metabolism, and changes in the nervous system that reduce arousal. However, compared to wakefulness, during sleep our breathing is slower and deeper, but not much less in terms of oxygen intake. In contrast, when meditating, as the mind calms down and the body needs less oxygen to function, the respiratory rate can drop dramatically.
The health benefits of meditating regularly are well documented, but it is important to note that the effects of not meditating are not as disastrous as sleep deprivation. In one experiment, meditators had significantly shorter sleep durations than non-meditators (5.2 vs 7.8 hours per day). This suggests that meditation can provide at least short-term performance improvement, even for novice meditators. Neuroimaging studies are beginning to support the idea that a meditation practice promotes greater wakefulness and less propensity for sleep as it progresses in intensity.
It is important to remember that, as far as the body is concerned, meditation and sleep are two different things. In experiments with experienced long-term meditators, sleep duration was measured using sleep diaries and actigraphy. Sleep deprivation produced a slower initial reaction time (RT) in PVT that still improved significantly after a period of meditation. This suggests that meditation plays a performance-enhancing and perhaps restorative role even in novice meditators. Ultimately, it is up to each individual to decide how much sleep they need and how much meditation they should practice.
However, it is clear that both activities have their own unique benefits and can be used together to promote overall wellbeing.
