Biomedical subjects
Publications and source records attributed to M Weissbluth.
It is hypothesized that melatonin, by its actions on porphyrin and nitric oxide biosynthesis, produces an increase in cyclic guanosine monophosphate.
Colic is periodic behavior occurring at the end of the day during the first 3 months of life characterized by crying. It is hypothesized that the crying at the end of the day is due to sleep inertia or a state dissociation during which the infant is simultaneously partially awake and partially asleep because of the absence of a melatonin diurnal rhythm. The melatonin timing mechanisms, which codes for day length, is initiated prenatally by the maternal pineal gland, and after 3 months postnatally, the melatonin nocturnal secretion rhythm is maintained by the infant's pineal gland. To record the seasonal variation in day length away from the equator, 12 months are required to complete the melatonin chemical calendar. This circannual process is only 9 months completed at the time of birth, and 3 additional months are needed during which the infant may have difficulty reconciling cues for the timing of evening sleep due to discrepancies between the expected photoperiod derived from the prenatal maternal pineal melatonin circadian rhythm and the postnatally experienced photoperiod. Data is presented showing that the incidence of colic increases with increasing latitude in support of the hypothesis that infant crying at the end of the day during the first 3 months represents the last quarter of a circannual photoperiodic development process.
It is hypothesized that in the evening, peak serotonin concentration causes intestinal cramps associated with colic because serotonin increases intestinal smooth muscle contractions. Melatonin has the opposite effect of relaxing intestinal smooth muscles. Both serotonin and melatonin exhibit a circadian rhythm with peak concentrations in the evening. However, serotonin intestinal contractions are unopposed by melatonin during the first 3 months because only serotonin circadian rhythms are present at birth. Melatonin circadian rhythms appear at 3 months of age. The cramps of colic disappear at 3 months of age.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
To obtain age-specific normative data, we performed home cardiorespiratory recordings (pneumograms) in 56 normal infants at 1 month of age. A repeat pneumogram was performed at 3 months in 39 infants. Total sleep time was determined and all sleep intervals were summed and analyzed for five respiratory pattern variables: frequency of all apneic episodes greater than or equal to 6 seconds in duration (A6/D%), periodic breathing, longest apneic episode, and number of episodes greater than 11 and greater than 15 seconds. The normal infants at 1 and at 3 months were compared with 66 patients with apnea of infancy. Median A6/D% was 0.1 in the normal infants at 1 and 3 months, compared with 0.64 in those with apnea of infancy (P less than 0.001). Median periodic breathing was 0.4 and 0.2 episodes per 100 minutes in the normal infants at 1 and 3 months, respectively, compared with 1.25 in infants with apnea of infancy (P less than 0.001). Median longest apneic episode was 8.0 seconds in the normal infants at 1 and 3 months, compared with 11 seconds in those with apnea of infancy (P less than 0.001). No normal infant had an apneic episode greater than 15 seconds in duration, whereas the group with apnea of infancy had 0.4 +/- 1.0 episodes of apnea of greater than 15 seconds (P less than 0.01). Despite these significant group differences, use of these respiratory patterns either alone or in combination permitted only about 80% correct classification of normal infants and those with apnea of infancy.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
We performed a prospective, randomized, double-blind, placebo-controlled clinical trial of dicyclomine hydrochloride using specific diagnostic criteria for infantile colic: spells of unexplained irritability, agitation, fussiness or crying lasting greater than or equal to 3 hours/day, occurring greater than or equal to 3 days/week, and continuing for greater than or equal to 3 weeks. Dicyclomine eliminated colic in 15 of 24 (63%) infants, whereas placebo was effective in six of 24 (25%) (corrected X2 = 5.42, P = 0.02). The study also addressed the hypothesis that parental distress caused by infantile colic affects subsequent temperament and sleep patterns. The data fail to document easier temperaments or longer sleep durations at 4 months in infants whose colic ceased during treatment.
Parental reports of night waking and sleep patterns were obtained for 141 normal 4- to 8-month-old infants from middle-class families. A group of infants was identified who had a past history of colic and who were perceived to have a current night waking "problem." These infants awoke more often than other infants and also had significantly briefer total sleep duration. Night waking was described as a problem in infant boys more often than in infant girls. A second group of infants who awoke frequently was reported to snore or mouth breathe when asleep. This group of infants did not have a past history of colic, was not perceived to have a night waking problem, and was not overly represented by boys. Ordinal position, father's education level, gender, and method of feeding did not affect reported sleep patterns.
Progesterone and its metabolites are potent depressors of the central nervous system. Plasma progesterone concentrations significantly correlated with temperament ratings for approach/withdrawal (r = -0.35, p = 0.01) and intensity (r = -0.28, p = 0.04) among 42 normal infants. The median age at the time of the progesterone sample was 36 days. Easier infants tended to have higher plasma progesterone concentrations compared with more difficult infants (mean +/- SEM: 25 +/- 4 ng/dl versus 17 +/- 3 ng/dl, p = 0.15). Results are consistent with the hypothesis that progesterone or its metabolites may exert a behavioral depressor effect in infancy.
Parental reports of sleep patterns, ratings on the Behavioral Style Questionnaire, and Conners' Abbreviated Parents' Questionnaire were obtained for 60 three-year-old children. Children who were more adaptable, mild, and positive in mood, or children with an easy temperament, had longer total sleep durations and lower Conners' ratings than children with opposite traits. Adaptability was the temperament characteristic most highly correlated with total sleep duration and the only characteristic which correlated with the number of night wakings. In addition, children with low activity ratings had long total sleep durations, low Conners' ratings, and were described as having a quiet sleep pattern. Long sleep durations and low Conners' ratings appear to be features of children with an easy temperament or low motor activity when awake and asleep.
Explore the source record for details and available documents.
Infant temperament ratings and parental reports of sleep patterns and sleep durations were obtained on 105 normal infants. Boys with more difficult temperaments and active sleep patterns had brief attention spans compared to the other children (p = 0.005). Among all infants, active sleep pattern was associated with maleness and increased activity ratings when awake (both p less than 0.05). Infants with easy temperaments slept longer than those with difficult temperaments (14.9 +/- 0.2 versus 12.8 +/- 0.5 hours, p less than 0.001). Gender, maternal prenatal smoking, method of feeding, and infant sleep position did not affect attention span ratings or sleep durations.
This case control study of healthy children utilized parents' reports to determine whether behavioral, developmental, or academic problems were associated with signs of partial airway obstruction (snoring, difficult or labored breathing, and mouth breathing) during sleep. Results suggest an association between the signs of airway obstruction during sleep and problems when awake. Children with behavioral, developmental, or academic problems had a significantly later bedtime hour, briefer duration of total sleep, longer night awakenings, and an increased latency to sleep, as compared to children without those problems.
Explore the source record for details and available documents.