Effects of short duration morning bright light in healthy elderly. II: sleep and motor activity

Subjective sleep feelings and motor activity were measured in seven healthy elderly subjects for 6 days. The subjects were exposed to bright light (6000 lux) for 30 min in the morning or instructed to sit in front of a desktop lighting device without light. The average level of motor activity during the night was significantly decreased in the bright light condition, compared with the controlled condition. However, daytime motor activity did not show significant differences between the two conditions. From these findings, even a short duration of morning bright light is effective in maintaining sleep without changing daytime activity.     

Disruption of sleep recovery after 36 hours of exposure to moderately bright light

Eight young adults were exposed to either 36 hours of moderate bright light (BL; 1,000-2,000 lux) or a light/dark cycle (L/D < 50 lux) during constant routine. Sleep was recorded on the two subsequent recovery sleeps (R1 and R2) and compared to baseline. After the BL exposure, the rebound of stage 4 sleep and slow wave activity (SWA) were split over R1 and R2, whereas after the L/D cycle, the stage 4 sleep debt was almost completely compensated for during R1. During R1, stage 2 sleep and wakefulness accumulated faster in the BL condition than in the L/D condition. An elevation of the temperature level was also found during R1 of the BL condition. No differences between light conditions were found in urinary levels of melatonin or cortisol secreted during R1 or R2. Homeostasic process does not appear to be affected by the BL condition. A modification in the sleep-wake balance and a change in the temporal relationship between the circadian system and the sleep-wake cycle are discussed.     

Sound-induced seizures in serotonin 5-HT2c receptor mutant mice

OBJECTIVES: In previous University of California, San Diego (UCSD) studies, nocturnal illumination shortened menstrual cycles that were longer than 33 days. The studies reported here extend the previous findings, confining the illumination to the sleep period. DESIGN: Two light levels (235 to 250 lux and less than 1 lux) and 2 modes of light delivery (lighted sleep mask and bedside lamp) were tested. RESULTS: 235 to 250 lux treatment cycle lengths were significantly shorter than baseline, but not significantly shorter than the less than 1 lux treatment cycle lengths. Subjective reports of sleep disturbance were greater with the 235 to 250 lux treatment, but there was no significant difference in overall quality of sleep between the two light levels. CONCLUSIONS: The current data alone do not exclude spontaneous remission or suggestion, but our previous studies demonstrated significant contrasts between 235 to 250 lux and less than 1 lux light levels. This study suggests that treatment may be effective when confined to the sleep period, and that light masks, which do not disturb bed partners, may be used in place of bedside lamps.     

Bright light affects alertness and performance rhythms during a 24-h constant routine

The aim of the present study was to assess the stimulating effects of bright light (BL) on subjective and objective alertness. Eight subjects were exposed to either bright light or dim light (DL) during a 24-h constant routine (0900-0900). Bright light failed to modify either the 24-h course or the level of body temperature. Compared to DL, BL delayed the circadian trough of motor activity by 2 h. During the night, relative to the dim-light condition, BL significantly increased subjective and objective (EEG test) alertness and improved performances. Thus, BL exposure partly counteracted the effects of sleep deprivation and/or the circadian trough on alertness and performances. During the day, BL only improved the mood and motivation levels. However, the time course of mood and motivation was not affected by the BL exposure, a nocturnal circadian trough occurring at 0630 in both light conditions.     

Effects of fluoxetine versus bright light in the treatment of seasonal affective disorder

BACKGROUND: Disturbances of serotonergic neurotransmission appear to be particularly important for the pathophysiology of winter depression. This study investigated whether fluoxetine has antidepressant effects comparable to bright light in the treatment of seasonal affective disorder (winter type). METHOD: A randomized, parallel design was used with rater and patients blind to treatment conditions. One week of placebo (phase I) was followed by 5 weeks of treatment (phase II) with fluoxetine (20 mg per day) and a placebo light condition versus bright light (3000 lux, 2 h per day) and a placebo drug. There were 40 patients (20 in each treatment condition) suffering from seasonal affective disorder (SAD) according to DSM-III-R who had a total score on the Hamilton Depression Scale of at least 16. RESULTS: Forty patients entered phase II and 35 completed it (one drop-out in the fluoxetine group and four in the bright light group). Fourteen (70%) of the patients treated with bright light and 13 (65%) of those treated with fluoxetine were responders (NS). The remission rate in the bright light group tended to be superior (bright light 50%, fluoxetine 25%; P = 0.10). Light therapy improved HDRS scores significantly faster, while fluoxetine had a faster effect on atypical symptoms. Light treatment in the morning produced a significantly faster onset of improvement, but at the end of treatment the time of light application seemed not to be crucial. CONCLUSION: Both treatments produced a good antidepressant effect and were well tolerated. An apparently better response to bright light requires confirmation in a larger sample.     

The therapeutic focus in significant sessions of master therapists: a comparison of cognitive-behavioral and psychodynamic-interpersonal interventions

This study was designed to test the hypothesis that bright light (BL) can have a stimulating effect on vigilance even in the absence of suppression of melatonin secretion and that this effect can be detected when measured in subjects with low vigilance levels. Seven normal subjects were exposed to bright-white light (BL group) and seven to dim-red light (DL group) on 2 consecutive days, each following a night of 4-h sleep restriction. The light treatment was administered in the late morning, between 0900 and 1330 hours. Salivary melatonin measurements indicated that BL did not suppress melatonin secretion or induce circadian phase shifts. The effects of the two treatments were compared on validated measures of daytime vigilance: immediate effects were evaluated on subjective alertness during the light treatment, whereas short-term (0.5-10.5 h) and long-term (20.5-34.5 h) carryover effects were measured on subjective alertness, daytime sleep latencies (DSL), and psychomotor performance. After two nights of sleep restriction, subjective alertness and daytime sleep latencies decreased significantly, but there was no effect of the light treatment. BL treatment did not affect global performance, but there was an effect on the strategy used by the subjects, as shown by faster reaction times and increased percentage of errors in the BL group. It was concluded that daytime BL exposure did not have a stimulating effect on our measures of vigilance even in sleep-deprived subjects but that it may increase physiological arousal and affect the subjects' behavior in some specific performance tasks.     

Effects of two kinds of pillow on thermoregulatory responses during night sleep

We compared thermoregulatory responses during night sleep between two kinds of pillow. One has special cool medium consisting of sodium sulfate and ceramic fiber (pillow A) and the other polyester padding (pillow B). The subjects wore 100% cotton thin pajamas with short sleeves and three-quarters trousers for summer use. They lay and slept in bed with cotton sleeping mat and cotton quilt between 10:30 p.m. and 6:30 a.m. in a bed room with an ambient temperature (Ta) of 27 +/- 1 degrees C and a relative humidity of 55 +/- 5%, using either of the pillow A or pillow B. When they awoke, the subjects filled out a questionnaire on how well they slept during sleep. Main results were: 1) Rectal and forehead skin temperatures and heart rate were kept significantly lower in the pillow A during the latter half of the night sleep. 2) Palm and thigh skin temperatures were significantly higher mostly in the pillow A. 3) All the subjects regarded the pillow A better for deeper sleep. It was concluded that slight cooling of the head due to the pillow A during night sleep seemed to be of significance for deep sleep.     

Non-24-hour sleep-wake syndrome in a sighted man: circadian rhythm studies and efficacy of melatonin treatment

The case of a 41-year-old sighted man with non-24-hour sleep-wake syndrome is presented. A 7-week baseline assessment confirmed that the patient expressed endogenous melatonin and sleep-wake rhythms with a period of 25.1 hours. We sought to investigate the underlying pathology and to entrain the patient to a normal sleep-wake schedule. No deficiency in melatonin synthesis was found. Furthermore, normal coupling between the melatonin and sleep propensity rhythms was documented using an "ultrashort" sleep-wake protocol. Environmental light exposure was monitored for 41 days, and the circadian timing was calculated. Sensitivity to photic input was determined with light-induced melatonin-suppression tests. Three intensities (500, 1,000, and 2,500 lux) were examined during three separate trials. The 2,500-lux trial resulted in 78% suppression, but the lesser intensity exposures were without substantial effect. Thus, the patient appeared to be subsensitive to bright light. A 4-week trial of daily melatonin administration (0.5 mg at 2100 hours) stabilized the endogenous melatonin and sleep rhythms to a period of 24.1 hours, albeit at a somewhat delayed phase. A 14-month follow-up interview revealed that the patient continued to take melatonin daily, and his sleep-wake schedule was stable to a near 24-hour schedule.     

Dawn simulation treatment of abstinent alcoholics with winter depression

BACKGROUND: Recent data suggest that winter depression (seasonal affective disorder [SAD]) may be a subtype of affective disorder that is closely related to alcoholism. Dawn simulation has been shown in controlled trials to be effective in SAD. The present study examined the effectiveness of dawn simulation in abstinent alcoholics who met DSM-III-R criteria for major depression, or bipolar disorder, depressed with seasonal pattern. METHOD: All 12 subjects with winter depression had a history of either alcohol dependence or alcohol abuse according to DSM-III-R and had been abstinent from alcohol for at least 6 months. They also fulfilled criteria for SAD according to Rosenthal and were hypersomnic and drug free. After a 1-week baseline period, the subjects were randomly assigned to a 1-week treatment period at home with either a white 1.5-hour dawn from 4:30 a.m. to 6:00 a.m. peaking at 250 lux or a red 1.5-hour dawn from 4:30 a.m. to 6:00 a.m. peaking at 2 lux. The subjects were told that they would receive daily either a red or a white dawn reaching the same illuminance, an illuminance that would be much dimmer than standard bright light treatment. At the end of each week, the subjects were blindly assessed by a psychiatrist using the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorder version (SIGH-SAD). RESULTS: For the 6 subjects completing the white dawn treatment, the mean SIGH-SAD score decreased from 33.0 at baseline to 15.8 after treatment. For the 6 subjects completing the dim red dawn treatment, the mean SIGH-SAD score decreased from 34.3 to 32.7. The mean post-dawn SIGH-SAD score was significantly lower after the white dawn treatment than after the dim red dawn treatment (ANCOVA with baseline SIGH-SAD as the covariate, F = 12.95, p < .01). Superiority of the white dawn was also found by analogous analyses for the Hamilton Rating Scale for Depression (HAM-D) (p < .01) and the SAD Subscale (p < .05). CONCLUSION: The present study suggest that dawn simulation may be helpful in decreasing depression in abstinent alcoholics with SAD. Further study is necessary to confirm these preliminary findings and to determine whether dawn simulation might be helpful in preventing relapse in abstinent alcoholics who have SAD.     

Effects of light treatment on sleep structure in seasonal affective disorder

Twelve outpatients with seasonal affective disorder (depression, winter type) were treated by 1 h of bright light exposure for five mornings. The intervention produced a significant reduction in depression scores, but no change was seen in the sleep electroencephalographic variables recorded after light treatment. Significant changes were seen, however, in ratings of subjective sleepiness. The acrophase of the circadian sleepiness rhythm was phase advanced, the mean level of the sleepiness rhythm was diminished, and the mean values of sleepiness scores were reduced at 8 and 10 a.m. This minimal influence of bright light on sleep structure is unlikely to explain the well-documented antidepressant effect.     

Adapting to phase shifts, II. Effects of melatonin and conflicting light treatment

The effects of melatonin (MT) and placebo (P) on adaptation to a rapid 9-h advance phase shift, in the presence and absence of inappropriate bright light (BL) exposure were examined. Volunteers were initially subjected to a gradual 9-h delay phase shift over 5 days (D1-D5) using a combination of bright light and darkness/sleep. Readaptation to a subsequent rapid 9-h advance phase shift was studied using: 1) MT, 5 mg, 2300 h, D6-D8, 2) BL, 2,000 lx, 0800-1200 h, D7-D8, 3) MT+BL and 4) P, 2300 h, D6-D8. MT treatment was timed to phase advance and BL to phase delay. BL delayed the 6-sulphatoxymelatonin rhythm in five out of seven subjects. Two subjects delayed and five phase advanced with both MT and MT+BL. MT consistently improved subjective sleep, alertness, and performance even in the presence of inappropriate BL and before phase readaptation had occurred. BL improved alertness and performance transiently. The beneficial effects of MT are not wholly mediated through an effect on the biological clock.     

A multicenter study of the light visor for seasonal affective disorder: no difference in efficacy found between two different intensities

Fifty-five patients with winter seasonal affective disorder (SAD) were treated with a light visor, a newly developed portable light-delivery system, in a controlled parallel design. A dim (400 lux) visor was compared with a bright (6000 lux) visor for either 30 or 60 minutes in the morning for 1 week. Response rates for these two treatments were 36% and 56%, respectively; the duration of treatment sessions did not affect outcome. There was no evidence that the brighter visor was superior in efficacy to the dimmer one. Significantly greater relapse occurred following withdrawal of the dimmer visor. Alternative explanations for these findings are that the light visor is acting as a placebo or that it is equally effective over a wide range of intensities.     

Extraocular light exposure does not suppress plasma melatonin in humans

Light affects the circadian axis in at least two ways. It can cause the acute suppression of pineal melatonin synthesis, and/or a phase-shift of the circadian oscillator. As recent evidence has suggested that extraocular light exposure may cause phase-shifts of the circadian clock, we have investigated whether suppression of melatonin can be induced by the same type of light exposure. In the first study subjects' eyes were exposed to white light (2250 lux for 30 mins) via a fibre optic cable. As expected, suppression of nighttime plasma melatonin levels (61 +/- 6%) was observed. In the second study, light of the same quality but higher intensity (14,000 or 67,500 lux for 180 mins) was delivered in the same manner to the popliteal region behind the subjects' knees, whilst shielding their eyes. No suppression of plasma melatonin levels (4 +/- 7%) was detected in any of the subjects. Thus, extraocular photoreception, if it exists in mammals, does not affect the suprachiasmatic nucleipineal pathway.     

Circadian rhythms during gradually delaying and advancing sleep and light schedules

The circadian rhythms of the night shift worker show very little phase shift in response to the daytime sleep and night work schedule. One strategy for producing circadian adaptation may be to use appropriately timed exposure to high-intensity light. We attempted to shift the circadian temperature rhythms of seven normal subjects while they followed a sleep schedule that gradually delayed (2 h per day) until sleep occurred during the daytime, as is customary for workers during the night shift. After 5 days, the sleep schedule was gradually advanced back to baseline. High illuminance light (2 h per day) and the attenuation or avoidance of sunlight were timed to facilitate temperature rhythm phase shifts. In general, the temperature rhythm did not shift along with the sleep-wake schedule, but appeared either to free run or remain entrained to the natural 24-h zeitgebers. This study showed how difficult it can be to shift human circadian rhythms in the field, when subjects are exposed to competing 24-hr zeitgebers.     

Effects of the menstrual cycle on dressing behavior in the cold

The purpose of the present study was to determine the effect of the menstrual cycle on dressing behavior in cold exposure. Rectal and skin temperatures, temperature sensation and metabolic rate were measured in seven women during the luteal (L) and the follicular (F) phases of the menstrual cycle, as was their dressing behavior in these two phases. The subjects were instructed to dress so as to feel comfortable when the ambient temperature was decreased from 30 degrees C to 15 degrees C (07:00-09:00). Most subjects dressed more quickly and with thicker clothing in the L phase. They felt cooler in the L phase during the last 30 min of the temperature fall. Rectal and skin temperatures showed significant differences between L and F phases and metabolic rate was significantly higher in the L phase. The results can be interpreted in terms of the establishment of a higher set-point in core temperature during the L phase.     

Lipid mediators in the rat retina: light exposure and trauma elicit leukotriene B4 release in vitro

Light exposure not only elicits a visual response but may also alter functional and structural characteristics of the retina. Furthermore, light exposure can lead to reversible or irreversible lesions of photoreceptors and pigment epithelium. Previous studies in our laboratory have shown that light liberates arachidonic acid from retinal membrane phospholipids mainly by activating the phospholipase A2. In this study we show that light and trauma elicit the synthesis of leukotriene B4 in the isolated rat retina in vitro. Male albino rats were dark adapted for 36 h, isolated retinae were taken, incubated and exposed a) either to darkness or to 5,000 lux of cool white fluorescent light for 5, 10 or 15 min at 37 degrees C, b) either to darkness or to 5,000 lux of cool white fluorescent light for 15 min at 0 degrees C or c) either to darkness or to 5,000 lux of cool white fluorescent light for 15 min at 37 degrees C with a 5-lipoxygenase inhibitor (zileuton). Eicosanoids were extracted and leukotriene B4 levels were determined by radioimmunoassay. Removal of retinae and incubation in darkness caused a significant rise in leukotriene B4 levels with increasing incubation time. This rise was further augmented significantly after light exposure. The leukotriene B4 levels obtained when incubating the retinae either at 0 degree C or with the lipoxygenase inhibitor zileuton as well as the high specificity of the radioimmunoassay indicate that the light- and trauma-elicited synthesis of leukotriene B4 is mediated by activating the 5-lipoxygenase. Leukotriene B4 may be involved, at least in part, in the pathogenesis of retinal diseases including light damage. Curr. Eye Res. 14: 1001-1008, 1995.     

Disturbance of sleep in blindness

PURPOSE: To determine the prevalence and severity of sleep disturbance in blind subjects and its relation to the form and duration of visual loss. METHODS: Of 403 blind subjects (visual acuity of less than 20/200 or a visual field of less than 5 degrees) recruited for the study, 15 were excluded because of affective disorder as identified by Montgomery Asberg Depression Scale. The remaining 388 subjects and a comparison group of 44 normally sighted individuals underwent an interview, and the Pittsburgh Sleep Quality Index questionnaire was administered. Sleep disturbance was classified as mild, moderate, or severe. RESULTS: Disturbance of sleep was recorded in 189 (48.7%) of the blind subjects. The prevalence was higher and the sleep disturbance was more severe in those with no perception of light than in those with light perception or better visual acuity. In the comparison group, four (9.1%) had mild sleep disturbance only. The differences between blind subjects and normally sighted individuals were highly significant (P < .001). The most common sleep-related problem among the blind subjects was interrupted sleep, followed by increased sleep latency, short sleep duration, and daytime naps. Among the blind subjects, no correlation was found between the extent of sleep disturbance and the duration and pattern of visual loss. CONCLUSIONS: Blind subjects who retain light perception, as well as those with total loss of vision, have a high frequency of sleep disturbance, although disorder is more common and more severe in subjects with no light perception. Management of the sleep disturbance may improve the quality of life in the visually handicapped.     

The "seat belt mark" sign: a call for increased vigilance among physicians treating victims of motor vehicle accidents

The light-induced phase-resetting response of the locomotor activity rhythm in the field mouse Mus booduga was studied at two phases of the circadian cycle known to respond to light stimuli of 15 min duration and 1000 lux intensity with maximum advance (at circadian time 20 [CT20]) and maximum delay phase-shifts (at CT15). The phase-shifts evoked by natural daylight stimuli of various illuminations ranging between 0.001 lux and 10,000 lux and lasting 15 min were estimated. The results clearly demonstrate that the relationship between the phase-shifts and the intensities of light stimuli is nonlinear. Furthermore, a single light stimulus of 0.001 lux, or 0.1 lux intensity for a duration of 15 min, administered at CT20, evoked unequivocal responses; phase delays were observed instead of phase advances. The critical intensities needed for light stimuli of 15 min duration to induce saturating response were calculated and were found to be about 100 lux for CT20 and about 500 lux for CT15. These results suggest that a greater intensity of light is required at the phase CT15 to induce a saturating phase shift than is required at a later phase of the circadian cycle (CT20).     

Treatment and outcome of patients with acute myocardial infarction and prior cerebrovascular events in the thrombolytic era: the Israeli Thrombolytic National Survey

Changes in sleep after fetal preoptic (POA) tissue transplantation were studied in rats which had been made insomniac by a medial preoptic area (mPOA) lesion. Two days after the N-methyl D-aspartic acid (NMDA) lesion of the mPOA, fetal POA tissues (obtained from 14- to 17-day-old fetuses) were transplanted into the lesioned mPOA. Insomnia was less marked in these animals, as compared to nontransplanted lesioned rats, even on the 4th day after transplantation. The quantum of sleep nearly attained the prelesion level by the 20th day. Body weight also showed recovery after transplantation. Rectal temperature, which was increased by the lesion of the mPOA, remained unaltered even after the transplantation. These results suggest that the recovery of sleep and rectal temperature may follow different time courses. Surviving transplanted neurons were seen at the site of lesion on postmortem examination. Humoral interaction between the host and the transplant may be responsible for the early recovery of sleep, though the establishment of neural connections between the host and transplant might have contributed to the later recovery. This is the first study to show the recovery of sleep function in insomniac animals after fetal preoptic tissue transplantation. However, the specificity of the POA fetal tissue, in comparison with other neural tissues to promote sleep recovery, remains to be established.     

Morning vs evening light treatment of patients with winter depression

BACKGROUND: According to the phase-shift hypothesis for winter depression, morning light (which causes a circadian phase advance) should be more antidepressant than evening light (which causes a delay). Although no studies have shown evening light to be more antidepressant than morning light, investigations have shown either no difference or morning light to be superior. The present study assesses these light-exposure schedules in both crossover and parallel-group comparisons. METHODS: Fifty-one patients and 49 matched controls were studied for 6 weeks. After a prebaseline assessment and a light/dark and sleep/wake adaptation baseline week, subjects were exposed to bright light at either 6 to 8 AM or 7 to 9 PM for 2 weeks. After a week of withdrawal from light treatment, they were crossed over to the other light schedule. Dim-light melatonin onsets were obtained 7 times during the study to assess circadian phase position. RESULTS: Morning light phase-advanced the dim-light melatonin onset and was more antidepressant than evening light, which phase-delayed it. These findings were statistically significant for both crossover and parallel-group comparisons. Dim-light melatonin onsets were generally delayed in the patients compared with the controls. CONCLUSIONS: These results should help establish the importance of circadian (morning or evening) time of light exposure in the treatment of winter depression. We recommend that bright-light exposure be scheduled immediately on awakening in the treatment of most patients with seasonal affective disorder.