About this Research Topic
Sleep and waking states are instinctual, circadian and rhythmic behaviors in animals. Although these states can be subjectively classified based on behaviors, their objective classification was made possible by the use of electrophysiological signals that distinguish each state. Using these signals, sleep in higher animals has been objectively classified into rapid eye movement sleep (REMS) and non-REMS (NREMS). Normally REMS appears after a period of NREMS, and since sleep is subject to circadian regulation, REMS also follows or is modulated by a circadian rhythm, which may not be as apparent. Many factors which show circadian rhythmicity have been shown to affect REMS. REMS deprivation (REMSD) also has been shown to affect most of circadian rhythmic functions e.g. thermoregulation, hormonal regulation, blood pressure, mood swings and so on; it also affects non-circadian related body functions e.g. memory, aggressiveness, and so on. Thus, these functions may be mediated by brain regions typically associated with REMS generation and their interactions with other neural systems.
The noradrenaline (NA)-ergic REM-OFF neurons in the locus coeruleus (LC) cease firing during REMS and they continue activity during REMSD. It is also known that NA level increases during REMSD. NA is known to modulate most psycho-somatic patho-physiological disorders, their associated behaviors and vice versa. Therefore, it is likely that the NA and LC neurons play a significant role, possibly by interacting with other brain regions, for inducing changes in REMS loss-associated disorders including circadian functions. This issue will focus on the current state-of-the-art science with respect to the role of the NA-ergic system and LC neurons in REMS regulation, their relationship with circadian rhythms and the endogenous and exogenous factors that can impact this relationship and vice versa. Original articles, short communication and review articles on the general ideas mentioned above will be published.
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