Vitamin B2 in Yu Sleep

Yu Sleep's Supplement Facts panel lists 0.5 mg of vitamin B2, as riboflavin 5-phosphate, the first of only three ingredients in the formula with a stated amount, and it is our Yu Sleep review that goes through what the other nine do. The other two disclosed amounts on the label are vitamin B6 at 0.5 mg and melatonin at 0.9 mg; the remaining seven ingredients sit inside a 637 mg "Proprietary Blend" with no individual amount given. This page checks that 0.5 mg B2 dose against the one human study that has tested vitamin B2 for sleep, and against the vendor's own claim about the form it uses.

What vitamin B2 does for sleep

Yu Sleep's sales letter says it uses vitamin B2's "bioactive, coenzyme" form, riboflavin 5-phosphate, for "much faster absorption and immediate activation" than generic B2, but that absorption claim has no cited source, and no study shows B2 in any form improving sleep at the 0.5 mg Yu Sleep discloses. The letter pairs this with vitamin B6, saying the formula uses "their bioactive, coenzyme forms: Riboflavin-5-Phosphate and Pyridoxal-5-Phosphate" instead of "generic Vitamin B2 and Vitamin B6" for that same absorption reason (text sales letter, paragraphs 570 to 571). Part of that statement holds up: riboflavin 5-phosphate is the coenzyme form the label discloses, and it matches the form NIH's own fact sheet names as the body's active form of the vitamin. The other part does not: "much faster absorption" is not backed by a cited trial anywhere in the vendor's material, and it says nothing about whether 0.5 mg of B2, in any form, changes sleep. Our look at Yu Sleep's absorption claims covers the "99% absorption" figure that runs across the whole formula, not just this one vitamin.

The evidence for vitamin B2

Ingredient-evidence.md rates vitamin B2's evidence for sleep "none" at Yu Sleep's dose: the only human trial found used 100 mg of B2 together with 100 mg of B1 for 4 weeks in 43 university students, and even then the two groups did not start at the same sleep-quality score. The table below names that trial in full.

Tao and colleagues ran their trial at Macau University of Science and Technology between January and March 2025, giving 43 volunteers a combined daily dose of 100 mg vitamin B2 and 100 mg vitamin B1 for four weeks. Sleep quality, measured on the Pittsburgh Sleep Quality Index (PSQI), improved in the supplement group and worsened in the placebo group, but the two groups did not start at the same score, so the result cannot be read as a clean before-and-after comparison. No trial has tested vitamin B2 alone, at any dose, for sleep, and none has tested it anywhere near Yu Sleep's 0.5 mg.

The dose in Yu Sleep vs the study dose

Yu Sleep's 0.5 mg of B2 covers 38% of an adult's ordinary daily requirement, and it is 200 times smaller than the 100 mg dose (paired with 100 mg of B1) that is the only amount ever tested for sleep. That 38% figure comes from the label's own percentage, built on the 1.3 mg daily value for vitamin B2, so one serving of Yu Sleep supplies under half of a routine daily need before any question of a sleep benefit even comes up.

• Yu Sleep's B2 dose: 0.5 mg (38% of the 1.3 mg daily value).
• The only sleep trial's dose: 100 mg B2, combined with 100 mg B1, which Yu Sleep does not contain.
• Gap between the two: about 200 times.

No trial has tested B2 anywhere near 0.5 mg, alone or in combination, for sleep. For how this dose sits alongside the formula's other nine ingredients, see Yu Sleep's full ingredient list.

Safety and interactions

Vitamin B2 has one of the widest safety margins of any Yu Sleep ingredient: no upper intake limit has been set for riboflavin at all, because even 400 mg a day, 800 times Yu Sleep's 0.5 mg, has not been shown to cause harm. The NIH Office of Dietary Supplements states that adverse effects from high riboflavin intakes, from food or supplements, have not been reported even at 400 mg a day for at least three months, which is why no Tolerable Upper Intake Level has been established for it. No clinically relevant drug interactions are known for vitamin B2 either. Against that margin, Yu Sleep's own 0.5 mg is a routine, food-level amount with no known risk at this dose. See Yu Sleep side effects for the full safety picture across all 10 ingredients, including the ones with an undisclosed amount.

Vitamin B2 alone vs vitamin B2 inside Yu Sleep

A stand-alone vitamin B2 supplement lets you match the ordinary 1.3 mg daily requirement and read the exact number on the label; inside Yu Sleep, B2 is fixed at 0.5 mg, one of three disclosed doses among ten ingredients. The other two disclosed amounts, melatonin at 0.9 mg and vitamin B6 at 0.5 mg, sit alongside B2 on the label, while the remaining seven ingredients share an undisclosed 637 mg blend. Choosing the coenzyme form, riboflavin 5-phosphate, over "generic" B2 is the vendor's own choice, made on a faster-absorption claim with no cited source, and whether that form matters at a 0.5 mg dose, one far below anything a sleep trial has tested, is not something any study has examined. Whether the liquid form itself changes absorption is a separate question, and one our look at Yu Sleep's absorption claims covers for the whole formula rather than repeating here.

Bottom line

On its own, Yu Sleep's 0.5 mg of B2 is a routine, low-risk vitamin dose with no sleep evidence behind it at that amount; whether the formula as a whole does anything for sleep is the question our Yu Sleep review answers for the product overall. The only relevant trial used 200 times as much B2, combined with a vitamin (B1) that Yu Sleep does not contain, and even that trial's two groups did not start at the same sleep-quality score. Of the 14 readable buyer reports we analyzed for Yu Sleep overall, 64% report no noticeable effect and 14% report improved sleep, too small a sample to credit or blame any single ingredient, B2 included.

FAQ

How much vitamin B2 is in Yu Sleep? 0.5 mg per 2 mL serving, as riboflavin 5-phosphate, equal to 38% of the daily value.

Does vitamin B2 help you sleep? No sleep-specific evidence exists at this dose. The only human trial that tested B2 for sleep used 100 mg of B2 together with 100 mg of B1, 200 times Yu Sleep's amount, and the two study groups did not start at the same sleep-quality score.

Why does Yu Sleep use "riboflavin 5-phosphate" instead of plain vitamin B2? The vendor says this coenzyme form absorbs faster and activates immediately. The forms match what NIH calls the coenzyme forms of B2, but the "much faster absorption" claim has no cited source, and no trial shows a sleep benefit from either form at 0.5 mg.

Is 0.5 mg of vitamin B2 safe? Yes. No upper intake limit has been established for riboflavin. Adverse effects have not been reported even at 400 mg a day for at least 3 months, and no clinically relevant drug interactions are known.

Is a separate vitamin B2 supplement better than Yu Sleep? It depends what you want. Alone, you can match the ordinary 1.3 mg daily requirement and know exactly what you are taking. In Yu Sleep it is fixed at 0.5 mg alongside nine other ingredients, three disclosed and seven not.