A supplement is usually described by what is in it. Less often we talk about when it is taken, even though the body does not behave the same way at seven in the morning and at ten at night.
Some things belong in the morning
Caffeine is the obvious case. Taken late, it can still be active at bedtime, because its half-life is several hours. That is why Clearhead, our only formulation with caffeine, is meant for mid morning and carries a note not to take it after 14:00.
Vitamins that are taken with food, such as vitamin D, suit a meal. Breakfast is the meal most people eat at a regular time, so Daybreak is built around it.
Some things belong in the evening
Magnesium and glycine are the two ingredients we move to the end of the day. Neither is a sedative, and we do not describe them as one. We place them in the evening because that is when people are looking for a wind-down, and because a larger magnesium dose is easier on the stomach later in the day.
What we do not know
Timing research for supplements is thinner than for medicines. Much of what we know comes from small studies, and some of it is based on what people report about their own sleep and energy.
For that reason we treat our timing as a sensible default, not a rule. If a different hour suits you better, move it, and tell us what you found.