On light as an alerting stimulus at night
Mariana G Figueiro1, John D Bullough, Andrew Bierman
1Lighting Research Center, Rensselaer Polytechnic Institute 21 Union Street, Troy, NY 12180, USA. figuem@rpi.edu.
Acta Neurobiologiae Experimentalis
|August 19, 2007
Summary
Nighttime blue light exposure increases alertness, similar to its effects on circadian regulation. This suggests the suprachiasmatic nucleus influences both nocturnal alertness and the body's internal clock.
Area of Science:
- Chronobiology
- Neuroscience
- Ophthalmology
Background:
- Light exposure at night can increase alertness.
- The precise relationship between light, nocturnal alertness, and circadian regulation requires further investigation.
Purpose of the Study:
- To determine if the functional relationship between light and nocturnal melatonin suppression is identical to that between light exposure and nocturnal alertness.
Main Methods:
- Four levels of narrow-band blue light were administered during nighttime sessions.
- Alertness was measured using the alpha attenuation coefficient (AAC) and the Norris mood scale.
- Electroencephalographic (EEG) alpha power density with eyes open and closed was recorded.
Main Results:
- Both AAC and alertness ratings increased with light irradiance.
- Alertness measures demonstrated a strong positive correlation with irradiance.
- Alertness measures were highly correlated with model predictions of nocturnal melatonin suppression.
Conclusions:
- The suprachiasmatic nuclei (SCN) play a significant role in regulating nocturnal alertness.
- The findings support the inference that the SCN is crucial for both circadian regulation and nocturnal alertness.
- Nocturnal alertness is influenced by light in a manner analogous to circadian regulation.
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