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. 2016 Nov 23;7(4):255–260. doi: 10.1016/j.jaim.2016.09.004

Table 1.

Description of the studies on dharana and dhyana.

Sl No Citation Sample size Design Variables Results Cohen's d Interpretation
1 Telles et al. (2013) 30 Random allocation of participants to four sessions Heart rate variability, respiration, photo-plethysmogram and skin resistance During dhyana
  • 1.

    skin resistance level increased

  • 2.

    photo-plethysmogram amplitude increased

  • 3.

    heart rate decrease

  • 4.

    breath rate decreased

  • 5.

    low frequency power decreased

  • 6.

    high frequency power increased

  • 7.

    NN50 count increased

  • 8.

    pNN50 increased
  • 1.

    0.472

  • 2.

    0.223

  • 3.

    0.502

  • 4.

    0.938

  • 5.

    0.745

  • 6.

    −0.733

  • 7.

    −0.307

  • 8.

    −0.260

 The changes were suggestive of reduced sympathetic activity and/or increased vagal modulation
2 Travis (2011) 26 Random allocation of participants to two groups Coherence, amplitude and eLORETA, sLORETA EEG analysis TM-Sidhi practice was characterized by higher frontal alpha1 and beta1 amplitudes, and eLORETA-identified sources of alpha1 EEG in right hemisphere object recognition areas including the right parahippocampus gyrus, right fusiformgyrus, lingual gyrus, and inferior and medial temporal cortices Alpha 1 (0.937), Beta 1 (0.872) The observed brain patterns support the descriptions of sanyama as including both specificity (sutras or verses), as suggested by higher frontal beta1 EEG amplitude and by eLORETA sources in right-hemisphere object recognition areas, and holistic experience (pure consciousness) as suggested by higher frontal alpha1 EEG amplitude.
3 Kumar et al. (2010) 30 Random allocation of participants to four sessions Short latency auditory evoked potentials The peak latency of a component called wave V was significantly increased during dharana, random thinking and focusing, but not during dhyana Dharana wave V peak latency (−0.368), random thinking (−0.343) and focusing (−0.378) Information transmission along the auditory pathway was delayed during dharana, random thinking and focusing but there was no change during dhyana
4 Telles et al. (2012) 60 Random allocation of participants to four sessions Mid-latency auditory evoked potentials During dhyana latencies of the Na and Pa waves were prolonged Na wave (−0.311) and Pa wave (−0.377) The auditory transmission at the level of the medial geniculate and primary auditory cortex was delayed during dhyana.
5 Telles et al. (2015) 60 (48 final) Random allocation of participants to four sessions Long latency auditory evoked potentials
  • 1.

    Peak latency of the P2 component decreased during and after meditation

  • 2.

    Peak amplitudes of the P1, P2 and N2 components decreased during random thinking and non meditation focused thinking
  • 1.

    Dhyana: During (0.614), Post (0.702)

  • 2.

    Amplitude: random thinking

  • P1 (0.675), P2 (0.656), N2 (0.679);

  • non meditative focused thinking:

  • P1 (0.540), P2 (0.615), N2 (0.561)

 Dhyana facilitates the processing of auditory information in the auditory association cortex, whereas the number of neurons recruited was less in random thinking and non meditative focused thinking at the level of the secondary auditory cortex, auditory association cortex and anterior cingulated cortex
6 Telles et al. (2015) 26 (10 long term experienced meditators and 16 less experienced meditators) Block design with random thinking, focusing, dharana and dhyana in a fixed sequence Functional brain images During dhyana the experienced meditators alone showed significant activation in the right middle temporal cortex (rMTC), right inferior frontal cortex (rIFC) and left lateral orbital gyrus (LOG) Not available on the data in the manuscript These changes suggest that dhyana is associated with sustained attention, memory, semantic cognition, creativity and an increased ability to detach mentally.
7 Adhia, Nagendra and Mahadevan (2010) 84 (42 in each group) Two group study (Yoga group and physical exercise group) Emotional intelligence, body mass index, blood pressure and blood sugar Emotional intelligence improved only in the Yoga group −0.839 The results indicate the importance of Yoga including dharana and dhyana as an integral element in improving managerial performance in organisations
8 Kumar and Telles (2009) 70 (35 in experimental group and 35 in control group) Random allocation of participants in the experimental group to four sessions Six letter cancellation The net scores on the six-letter cancellation task were significantly higher after a session of dharana no significant change after dhyana −0.406 Dharana may favorably influence selective attention, concentration, visual scanning abilities, and a repetitive motor response compared to other sessions