On–off switching of theta–delta brain waves related to falling asleep and awakening

The monoscale time span transitions from minutes-to-minutes are examined in relation to the interaction of delta and theta waves. Sustainability and stability of the delta and theta waves are evaluated by the severity of the oscillatory behavior of the least variance, a principle established for ranking cell growth. The relative order or disorder of delta and theta waves can be applied to distinguish the difference between falling asleep (FA) and awakening (AW). The brain wave frequency, amplitude and phase angles are regarded as the governing parameters in conjunction with the concept of synchronicity via the weighting functions.Awakening (AW) is found to be more controllable with a shorter time of sustainability as compared to falling asleep (FA). This corresponds to theta waves stabilized at a shorter time interval of 0–5 min than delta waves at 0–10 min. These results are based on the least variances averaged over the time span depicted. They are presented to encourage additional experiments on FA and AW.The monoscale time span study of delta–theta waves should be further reinforced by a dual scale time span of seconds-minutes with reference to the NREM and REM cycle of FA and AW. In particular, the direction of arrow from K-Complex (KC) to sleep spindle (SS) such as KC → SS deserves attention in relation to the reverse order of SS → KC. The reversal behavior may be associated with the N1 to N3 segment and N3 to REM segment of the FA–AW cycle. The monoscale study provides the impetus to further study the multiscale time span behavior of brain waves in general.