Can Folsäure help with Schlaf?

The question of whether folic acid can improve sleep lacks robust scientific evidence. Folic acid (vitamin B9) is essential for cell division and the synthesis of neurotransmitters like serotonin, which influences sleep-wake cycles. Theoretically, a deficiency could impair sleep, but in well-nourished individuals, supplementation offers no proven benefit. Most people in developed countries are not folate-deficient. Some marketers promote folic acid or methylfolate for sleep, based on weak mechanistic links or MTHFR genotypes. Official guidelines (e.g., EFSA) do not recognize a causal effect on sleep. Moreover, excessive folic acid (above 1,000 µg/day) can be harmful, e.g., masking vitamin B12 deficiency. Without a confirmed deficiency or specific medical indication, taking folic acid for sleep is not recommended. Evidence: unclear. Sources: none in provided context.