Influence of light at night on melatonin suppression in children.
Level 3 - non-randomized controlled study
Non-randomized controlled physiological study comparing two age cohorts across experimental light conditions
PubMed 24840814 · doi:10.1210/jc.2014-1629
What was done
Thirty-three healthy primary school children (mean age 9.2 ± 1.5 years) and 29 healthy adults (mean age 41.6 ± 4.7 years) participated in two physiological experiments measuring salivary melatonin. In experiment 1, 13 children and 13 adults were tested under dim light (<30 lux) and moderately bright light (580 lux) in an experimental facility, alongside pupil diameter measurements. In experiment 2, 20 children and 16 adults were tested under laboratory dim light versus typical room lighting at home (mean illuminance 140.0 ± 82.7 lux).
What was found
In experiment 1, exposure to moderately bright light (580 lux) caused significantly greater melatonin suppression in children (88.2%, n = 5) than in adults (46.3%, n = 6; P < .01). In experiment 2, domestic room light significantly suppressed melatonin secretion in children (n = 15; P < .05), whereas adults showed no significant suppression (n = 11).
Why it matters
This study provides evidence that children are substantially more sensitive to light-induced nocturnal melatonin suppression than adults, showing marked hormonal suppression even at typical home lighting levels.
Limits
The final analyzable cohorts were very small, especially in experiment 1 where data from more than half of the participants were excluded due to unrisen baseline melatonin. Home lighting intensity varied widely (standard deviation 82.7 lux), and functional sleep or circadian phase shift outcomes were not reported in the abstract.
Cited by
- supports Developing children are more sensitive to evening light exposure than adults.