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Phase-shifting effects of bright morning light as treatment for delayed sleep phase syndrome

Clinical Psychobiology Branch, National Institute of Mental Health, Bethesda, Maryland 20892.
Sleep (Impact Factor: 5.06). 09/1990; 13(4):354-61.
Source: PubMed

ABSTRACT Bright light has recently been shown to have phase-shifting effects on human circadian rhythms. In this study we applied this effect to 20 patients with delayed sleep phase syndrome (DSPS) who were unable to fall asleep at conventional clock times and had a problem staying alert in the morning. In a controlled treatment study, we found that 2 h of bright light exposure in the morning together with light restriction in the evening successfully phase advanced circadian rhythms of core body temperature and multiple sleep latencies in these patients. This finding corroborates the importance of light for entraining human circadian rhythms.

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    • "Since Czeisler and others [1986] demonstrated a resetting effect of bright light, it has been well documented that bright light before nocturnal sleep significantly delays the core temperature (T c ) rhythm, independent of the timing of the sleep–wake cycle [Boivin and Czeisler 1998; Dijk and others 1991; Drennan and others 1989] and that bright morning light can reset the human circadian rhythm [Clodore and others 1990; Dijk and others 1989; Foret and others 1993; Kondo and others 2007; Rosenthal and others 1990; Scheuermaier and others 2010]. Regarding the effect of bright morning light on phase shifts of the circadian rhythm, Scheuermaier and others [2010] reported that light has a phase-dependent effect on the circadian pacemaker , and modifying habitual light exposure in older individuals could contribute to changes in the timing of circadian rhythms or the phase angle of entrainment. "
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    ABSTRACT: This study tested the hypotheses that 2-h exposure to morning bright light after waking may avoid a delay in nadir time for individuals who experience delayed nadir time after waking and may improve the morning rise in core temperature (Tc) due to residual effects of morning bright light on body temperature regulation. Eight young men were exposed to 110, 1000, and 4000 lx light for 2 h after waking at 7:00 AM. After 2-h exposure to a given illuminance, illuminance was controlled at 1000 lx until 12:00 PM. Rectal temperature (Tre) was measured as a proxy for Tc continuously from 12:00 AM on the prior night to 12:00 PM on the day of the experiment. To estimate body heat balance, skin temperatures and values for regional dry heat loss at seven sites were continuously measured from 8:00 AM to 12:00 PM, together with measurement of oxygen consumption and finger skin blood flow rate (SkBF) from 8:00 AM to 12:00 PM at 1-h intervals. Results indicated delays of a few minutes in nadir time with 1000 and 4000 lx, as opposed to a 120-min delay with 110 lx. In addition, Tre increased after 2-h exposure to 4000 lx light, probably due to the significantly (P < 0.01) lower mean skin temperature, SkBF, and dry heat loss compared to the other lighting conditions. Light exposure over 1000 lx may thus avoid substantial delays in nadir time, and light exposure over 4000 lx could restore Tc rhythm in a prompt manner due to residual effects of morning bright light on body temperature regulation.
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    • "Finally, desynchronous conditions may occur when circadian rhythms are misaligned due to imposed alterations in light–dark cycles and sleep–wake times. pharmacological administration of melatonin (Dahlitz et al., 1991; Herxheimer and Petrie, 2002; Lockley et al., 2000; Sack et al., 1991), light therapy (Boulos et al., 2002; Eastman, 1990; Eastman et al., 1995; Lack et al., 2005; Rosenthal et al., 1990; Samel and Wegmann, 1997), and promotion of lifestyles that allow for individual preferred sleep–wake times. In the following sections, these established circadian sleep disorders are used as templates for interpreting the most common sleep problems in children with autism. "
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    Neuroscience & Biobehavioral Reviews 12/2009; 34(5):755-68. DOI:10.1016/j.neubiorev.2009.11.017 · 10.28 Impact Factor
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    • "Bright light treatment for sleep onset insomnia A limited number of studies have used bright light stimulation to advance the endogenous rhythm of individuals with a delayed sleep phase [52] [53] [54] [55] [56]. The time and length of light exposure has varied from a single 4-h pulse administered 30 min after awakening [53] to two weeks of therapy with light administered between 06:00 and 09:00 h [55]. "
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    ABSTRACT: Circadian rhythms have a strong effect on the ability to sleep across the 24-h period. Maximum sleepiness occurs at the phase of lower endogenous core body temperature. This period is bracketed by two periods of alertness: a "wake-maintenance zone" occurring 6-10h before the time of core temperature minimum, and a "wake-up zone" occurring 4-7h after the minimum. Therefore, if the circadian rhythm drifts earlier with respect to the attempted sleep period, the wake-up zone can impinge on the end of the normal sleep period resulting in premature awakening and the development of early morning awakening insomnia. Similarly, a delay of the circadian rhythm can impose the wake-maintenance zone on the attempted bedtime and lead to sleep onset insomnia. Therefore, these two types of insomnia should be treatable with chronobiologic effects such as bright light and, possibly, melatonin administration. Bright light stimulation at normal wake-up time and melatonin administration 4-8h before normal bedtime can phase advance circadian rhythms to an earlier time. While morning bright light has been efficacious for sleep onset insomnia, evening melatonin administration has yet to be tested. Early morning awakening insomnia has been treated with phase delays imposed by evening bright light but not yet with morning melatonin administration. There is now sufficient evidence to warrant the consideration of chronobiologic manipulations such as bright light therapy for the treatment of chronic sleep onset and early morning awakening insomnia that show evidence of circadian delay or advance, respectively.
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