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Limited evidenceSleep & relaxation

Alpha-Lactalbumin

A whey protein fraction unusually rich in tryptophan, taken in the evening to raise brain serotonin. The mechanism is real and measurable, but the sleep trials that followed are small and contradictory.

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What the science says

  • Tryptophan availability and morning alertness Limited evidence

    The foundational trial found that evening intake of alpha-lactalbumin raised the plasma tryptophan-to-large-neutral-amino-acid ratio and improved morning alertness and brain measures of attention in poor sleepers. It was a small crossover study, and the outcome was next-morning function rather than sleep itself.

  • Sleep architecture in athletes Limited evidence

    A randomised trial in athletically trained people with sleep difficulties found that evening alpha-lactalbumin altered sleep architecture and reduced morning reaction time. Effects were on measured sleep stages more than on how much or how well people slept.

  • Habitual sleep quality Limited evidence

    A separate randomised trial from the same group found that pre-sleep alpha-lactalbumin did not improve habitual sleep or performance in sportspeople with sleep difficulties. Taken together, the literature is small, mixed, and confined mostly to athletes.

Dosage & safety

Studied doseTrials have used roughly 20–40 g of alpha-lactalbumin-enriched whey in the evening, typically 1–2 hours before bed. Ordinary whey protein isolate contains far less alpha-lactalbumin and is not equivalent.
SafetyA milk protein — unsuitable for anyone with milk allergy, and it contains lactose traces. Large evening protein doses can cause bloating or reflux in some people. No known drug interactions, but people on MAO inhibitors or serotonergic drugs should be cautious with large tryptophan loads. Not a treatment for chronic insomnia.

How to take it

TimingTake it in the evening, 1–2 hours before bed.
With food?Take it on its own or with a small carbohydrate snack rather than with a large protein meal, since other amino acids compete with tryptophan for entry into the brain.
Worth knowingOrdinary whey isolate is not a substitute — only buy products that state the alpha-lactalbumin content on the label.

Interactions

With medications

  • MAO inhibitors and other strongly serotonergic drugs

    Alpha-lactalbumin delivers an unusually large tryptophan load, the precursor to serotonin. Do not take large evening doses without asking your prescriber first

With other supplements

  • 5-HTP, L-tryptophan or melatonin

    All push the same serotonin-melatonin pathway, and stacking them adds grogginess without added benefit. Use one of them, not several

Well-established interactions only — this is not a complete list. Always tell your doctor and pharmacist what you take.

Frequently asked questions

Does alpha-lactalbumin help you sleep?

The evidence is limited and mixed: evening alpha-lactalbumin raises tryptophan availability and one small study found better morning alertness in poor sleepers, but a separate trial found no improvement in habitual sleep in sportspeople. It is not a treatment for chronic insomnia.

How much alpha-lactalbumin should you take before bed?

Trials used roughly 20–40 g of alpha-lactalbumin-enriched whey in the evening, typically 1–2 hours before bed. Take it alone or with a small carbohydrate snack rather than a large protein meal, since other amino acids compete with tryptophan.

Is regular whey protein the same as alpha-lactalbumin?

No. Ordinary whey protein isolate contains far less alpha-lactalbumin and is not equivalent, so only buy products that state the alpha-lactalbumin content on the label.

Can you take alpha-lactalbumin with 5-HTP, melatonin or antidepressants?

Use one sleep aid, not several: alpha-lactalbumin, 5-HTP, L-tryptophan and melatonin push the same pathway and stacking adds grogginess. If you take MAO inhibitors or strongly serotonergic drugs, ask your prescriber before large evening doses.

Scientific references

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