Did you know that each of us have a “chronotype” of either being a “morning type” or “evening type?” Chronotype is the natural inclination of your body to sleep at a certain time, or what most people understand as being an early bird versus a night owl. In addition to regulating sleep and wake times, chronotype has an influence on appetite, exercise, and core body temperature. It is responsible for the fact that you feel more alert at certain periods of the day and sleepier at others. Importantly, the use of light therapy to help normalize your circadian rhythm, wakefulness, reduce fatigue and improve sleep is optimized when timed according to your chronotype. I’m a morning chronotype, and according to the data, light therapy delivered at awakening is most effective for me.
When not using my desktop light box, I use this light therapy device called RE-TIMER (https://www.re-timer.com) for 20-30 minutes when I get up in the morning. The design looks funny but it allows you to be more productive (catch up on morning emails, news and medical journals while drinking my coffee) and not wake up your spouse from a bright light box shining on them.
You can use the Morningness-Eveningness Questionnaire (AutoMEQ) to find out your chronotype and what time of day to effectively use your light therapy devices: https://chronotype-self-test.info/index.php