The effects of light and caffeine on nighttime alertness, biomarkers and performance
Abstract
Two physiological systems affect the sleep/wake cycle and alertness, the circadian system and the homeostatic system. The circadian"" system send an alerting signal during the day and a sleeping signal at night. The homeostatic system, or sleep pressure, increases"" as time awake increases. When these two systems are aligned, the alerting effect by the circadian systemcounteracts the sleep pres"sure that is built over the course of the waking day.It has been well established that the circadian system is maximally sensitive" to short-wavelength (blue) light, but it is not known if or how light affects the homeostatic system. Our lab, the Lighting Researc""h Center at Rensselaer Polytechnic Institute (LRC/RPI), showed that night-time exposure to one hour of 40 lux at the cornea from a n"arrowband blue light (~max = 470 nm)strongly affected the circadian system as measured by melatonin suppression and induced sympath"etic activation as measured by cortisol elevation. In contrast, 40 lux of narrowband red light (~max = 640 nm) had no effect on mela"tonin suppression but did elevate cortisolconcentrations. Subsequent studies performed by the LRC/RPI have consistently shown that" red light will increase alertness as measured by EEG and, for some tasks, will increase performance. Caffeine is known to block a""denosine receptors in the brain, reducing the effects of the sleep buildup. The combined effects of light and caffeine on daytime an""d nighttime alertness have not, however, been fully elucidated.Proposed here is an innovative line of research to develop a more b"asic understanding of the interaction between light exposure and caffeine administration as they affect alertness and performance at" night when fatigue is greatest. The specific aims are to investigate how low levels of blue and red light exposure, administered al""one and in combination with caffeine affect alertness, performance and melatonin concentrations at night. Future studies can be desi"gned to specifically investigate how people with various sensitivities to caffeine and light respond to these two types of stimulants.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Sep 01, 2017
- Source ID
- N000141712669
Entities
People
- Mariana Figueiro
Organizations
- Office of Naval Research
- Rensselaer Polytechnic Institute
- United States Navy