Allows you to:

• set reminders for critical circadian events essential for health and vitality

• align your lifestyle with the light and dark cycles at your location

• learn more about the science and how to apply it to your daily life

The free version (LITE) has 3 daily notifications, but no alarms. The learn section is also restricted. The paid versions have full access to the learn section. FULL has unlimited notifications and alarms, while BASIC has 8 notifications and 5 alarms.

I personally purchased the FULL/paid version years ago now and it has earned every dollar I spent on it, since I use this app daily.

Since this app offers more customization and lets me set alerts and alarms based on those customizations, I use it for several critical daily alerts. For example:

• Daybreak/Relative to Sunrise: Given daybreak changes by 1 minute each day, I use this alarm to wake me up 30 minutes prior to sunrise each morning.

• Sunrise: Since transition periods are even more powerful for setting your circadian rhythm, I set my sunrise alarm to 1-2 minutes before sunrise, so I’m outside during the transition.

• UVA Rise, UVB Rise, and Sunset: I do the same (set my alerts for 1-10 minutes prior to each event).

• Solar Noon: I try to be outside regularly for solar noon, preferably to get full-body sun exposure for 20+ minutes each day. Sunbathing at solar noon is the (often) fastest way to produce Vitamin D, since the UV index is the highest, unless it’s cloudy, etc. Even when I can’t sunbathe, it’s still nice to step outside at this time.

And quite a number of other customized alert/alarm settings, which is not a feature available on MyCircadian.