Memorial Day Offer

Discover your mystery discount!

Phase response curve

Circadian Rhythms and Phase Response Curve: – Circadian rhythms are regulated by a system that governs the phase relationship of internal clocks with the external […]

« Back to Glossary Index

Circadian Rhythms and Phase Response Curve:
– Circadian rhythms are regulated by a system that governs the phase relationship of internal clocks with the external environment.
– The phase response curve (PRC) illustrates the relationship between the time of treatment administration and its effect on the circadian phase.
– Synchronization of physiological rhythms, especially the sleep-wake cycle, is crucial.
– Therapeutic interventions based on PRC curves are used for light and melatonin to adjust sleep timing.
– Light therapy and melatonin administration are common methods for adjusting sleep timing.

Light and Circadian Phase:
– The PRC shows the effect of light exposure on the circadian phase.
– Light exposure before bedtime delays the circadian phase, while exposure after bedtime advances it.
– Light therapy with specific lux levels is used to adjust sleep timing and treat affective disorders like seasonal affective disorder (SAD).
– The peak effect of light exposure coincides with the body temperature trough during sleep.

Melatonin and Circadian Phase:
– Melatonin’s PRC phase response is approximately 12 hours out of phase with light’s PRC.
– Exogenous melatonin has a phase-delaying effect at wake-up time and a phase-advancing effect later in the day.
– Endogenous melatonin production before bedtime helps regulate the sleep-wake schedule and influences sleep phase timing.
– Dim-light melatonin onset (DLMO) prepares the body for sleep and influences the circadian rhythm.

Additive Effects and Timing Interventions:
– Combining morning bright light and afternoon melatonin can produce a larger phase advance shift.
– Timing interventions according to PRCs can enhance phase shifting effects.
– Research by Victoria L. Revell et al. demonstrated the additive effects of bright light and melatonin on phase advancement.

Eye Response to Light and Other Considerations:
– Special cells in the human eye, ipRGCs, control the light entrainment effect, responding most to blue light in the 460–480nm range.
– Blue light significantly impacts circadian phototransduction, with the spectral opponency theory suggesting the addition of other spectral colors affects blue light’s effectiveness.
– Research supports the role of ipRGCs in light entrainment and circadian rhythm control.
– Additionally, exploring the impact of exercise on shifting circadian phases and the historical origin of the term “phase response curve” provide further insights into circadian rhythm studies.

Phase response curve (Wikipedia)

A phase response curve (PRC) illustrates the transient change (phase response) in the cycle period of an oscillation induced by a perturbation as a function of the phase at which it is received. PRCs are used in various fields; examples of biological oscillations are the heartbeat, circadian rhythms, and the regular, repetitive firing observed in some neurons in the absence of noise.[better source needed]

« Back to Glossary Index
This site uses cookies to offer you a better browsing experience. By browsing this website, you agree to our use of cookies.