Acute alerting effects of daytime exposure to specific wavelengths of light

This study is looking at whether exposure to different colours of light — particularly blue light — can reduce daytime sleepiness and improve alertness and performance on various mental tasks. Light affects our body clock and brain activity, and researchers want to understand whether specific wavelengths of light have stronger alerting effects. Participants will be exposed to controlled light conditions during the day and tested on sleepiness and performance tasks. You may be eligible if: - You are between 18 and 30 years of age - You are in good general health (male or female) - You have normal sleep patterns You may NOT be eligible if: - You have done shift work or night work in the past 3 years, or travelled across time zones in the past 3 months - You smoke, drink high amounts of caffeine or alcohol, or use recreational drugs - You are pregnant or planning to become pregnant - You have a history of psychiatric illness, seizures, migraines, or vertigo - You have any eye disease or abnormal light sensitivity - You have a history of drug or alcohol dependence - You have abnormal sleep patterns or a sleep disorder Talk to your doctor about whether this trial might be right for you.