The Experts below are selected from a list of 121401 Experts worldwide ranked by ideXlab platform
Melissa A St Hilaire - One of the best experts on this subject based on the ideXlab platform.
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human phase Response Curve to a single 6 5 h pulse of short wavelength light
The Journal of Physiology, 2013Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Melanie Ruger, George C Brainard, Charles A CzeislerAbstract:Key points • The human ∼24 h circadian pacemaker ensures appropriate timing of physiological, behavioural and metabolic events and is synchronized to the 24 h day primarily by the 24 h light–dark cycle. • The direction and magnitude of photic resetting depend on the timing of light exposure, and are described by a phase Response Curve (PRC). • The human circadian photoreception system is functionally and anatomically distinct from the visual system and employs a novel photoreceptor, melanopsin, which is maximally sensitive to short-wavelength (blue) visible light. • We constructed a PRC to 6.5 h of blue (480 nm) light and compared it with a prior 6.7 h white light PRC; the blue light PRC achieved ∼75% of the resetting Response of the white light PRC. • This study suggests that short-wavelength visible light exposures may be more efficient than traditional high-intensity white light exposures for treatment of circadian rhythm sleep disorders. Abstract The photic resetting Response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase Response Curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18–30 years) were studied for 9–10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 μW cm−2, 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of −2.6 h and 1.3 h, respectively. The 480 nm PRC induced ∼75% of the Response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–Response function for the effects of light on circadian resetting.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (~8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ~40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration-Response function for the effects of light on circadian resetting. © 2012 The Authors. The Journal of Physiology © 2012 The Physiological Society.
Charles A Czeisler - One of the best experts on this subject based on the ideXlab platform.
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human phase Response Curve to a single 6 5 h pulse of short wavelength light
The Journal of Physiology, 2013Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Melanie Ruger, George C Brainard, Charles A CzeislerAbstract:Key points • The human ∼24 h circadian pacemaker ensures appropriate timing of physiological, behavioural and metabolic events and is synchronized to the 24 h day primarily by the 24 h light–dark cycle. • The direction and magnitude of photic resetting depend on the timing of light exposure, and are described by a phase Response Curve (PRC). • The human circadian photoreception system is functionally and anatomically distinct from the visual system and employs a novel photoreceptor, melanopsin, which is maximally sensitive to short-wavelength (blue) visible light. • We constructed a PRC to 6.5 h of blue (480 nm) light and compared it with a prior 6.7 h white light PRC; the blue light PRC achieved ∼75% of the resetting Response of the white light PRC. • This study suggests that short-wavelength visible light exposures may be more efficient than traditional high-intensity white light exposures for treatment of circadian rhythm sleep disorders. Abstract The photic resetting Response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase Response Curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18–30 years) were studied for 9–10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 μW cm−2, 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of −2.6 h and 1.3 h, respectively. The 480 nm PRC induced ∼75% of the Response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–Response function for the effects of light on circadian resetting.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (~8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ~40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration-Response function for the effects of light on circadian resetting. © 2012 The Authors. The Journal of Physiology © 2012 The Physiological Society.
Sat Bir S. Khalsa - One of the best experts on this subject based on the ideXlab platform.
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human phase Response Curve to a single 6 5 h pulse of short wavelength light
The Journal of Physiology, 2013Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Melanie Ruger, George C Brainard, Charles A CzeislerAbstract:Key points • The human ∼24 h circadian pacemaker ensures appropriate timing of physiological, behavioural and metabolic events and is synchronized to the 24 h day primarily by the 24 h light–dark cycle. • The direction and magnitude of photic resetting depend on the timing of light exposure, and are described by a phase Response Curve (PRC). • The human circadian photoreception system is functionally and anatomically distinct from the visual system and employs a novel photoreceptor, melanopsin, which is maximally sensitive to short-wavelength (blue) visible light. • We constructed a PRC to 6.5 h of blue (480 nm) light and compared it with a prior 6.7 h white light PRC; the blue light PRC achieved ∼75% of the resetting Response of the white light PRC. • This study suggests that short-wavelength visible light exposures may be more efficient than traditional high-intensity white light exposures for treatment of circadian rhythm sleep disorders. Abstract The photic resetting Response of the human circadian pacemaker depends on the timing of exposure, and the direction and magnitude of the resulting shift is described by a phase Response Curve (PRC). Previous PRCs in humans have utilized high-intensity polychromatic white light. Given that the circadian photoreception system is maximally sensitive to short-wavelength visible light, the aim of the current study was to construct a PRC to blue (480 nm) light and compare it to a 10,000 lux white light PRC constructed previously using a similar protocol. Eighteen young healthy participants (18–30 years) were studied for 9–10 days in a time-free environment. The protocol included three baseline days followed by a constant routine (CR) to assess initial circadian phase. Following this CR, participants were exposed to a 6.5 h 480 nm light exposure (11.8 μW cm−2, 11.2 lux) following mydriasis via a modified Ganzfeld dome. A second CR was conducted following the light exposure to re-assess circadian phase. Phase shifts were calculated from the difference in dim light melatonin onset (DLMO) between CRs. Exposure to 6.5 h of 480 nm light resets the circadian pacemaker according to a conventional type 1 PRC with fitted maximum delays and advances of −2.6 h and 1.3 h, respectively. The 480 nm PRC induced ∼75% of the Response of the 10,000 lux white light PRC. These results may contribute to a re-evaluation of dosing guidelines for clinical light therapy and the use of light as a fatigue countermeasure.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–Response function for the effects of light on circadian resetting.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (~8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ~40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration-Response function for the effects of light on circadian resetting. © 2012 The Authors. The Journal of Physiology © 2012 The Physiological Society.
Steven W Lockley - One of the best experts on this subject based on the ideXlab platform.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–Response function for the effects of light on circadian resetting.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (~8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ~40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration-Response function for the effects of light on circadian resetting. © 2012 The Authors. The Journal of Physiology © 2012 The Physiological Society.
Joshua J Gooley - One of the best experts on this subject based on the ideXlab platform.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (∼8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ∼40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration–Response function for the effects of light on circadian resetting.
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human phase Response Curve to a 1 h pulse of bright white light
The Journal of Physiology, 2012Co-Authors: Melissa A St Hilaire, Sat Bir S. Khalsa, Richard E Kronauer, Charles A Czeisler, Joshua J Gooley, Steven W LockleyAbstract:The phase resetting Response of the human circadian pacemaker to light depends on the timing of exposure and is described by a phase Response Curve (PRC). The current study aimed to construct a PRC for a 1 h exposure to bright white light (~8000 lux) and to compare this PRC to a <3 lux dim background light PRC. These data were also compared to a previously completed 6.7 h bright white light PRC and a <15 lux dim background light PRC constructed under similar conditions. Participants were randomized for exposure to 1 h of either bright white light (n= 18) or <3 lux dim background light (n= 18) scheduled at 1 of 18 circadian phases. Participants completed constant routine (CR) procedures in dim light (<3 lux) before and after the light exposure to assess circadian phase. Phase shifts were calculated as the difference in timing of dim light melatonin onset (DLMO) during pre- and post-stimulus CRs. Exposure to 1 h of bright white light induced a Type 1 PRC with a fitted peak-to-trough amplitude of 2.20 h. No discernible PRC was observed in the <3 lux dim background light PRC. The fitted peak-to-trough amplitude of the 1 h bright light PRC was ~40% of that for the 6.7 h PRC despite representing only 15% of the light exposure duration, consistent with previous studies showing a non-linear duration-Response function for the effects of light on circadian resetting. © 2012 The Authors. The Journal of Physiology © 2012 The Physiological Society.
