howtosupplement
Sleep/Mood/Women

L-Tryptophan

Essential amino acid and serotonin precursor that may improve sleep quality and mood in adults with mild sleep issues.

L-Tryptophan

L-Tryptophan

58
score
C
evidence
Caution
risk
Quick Take

Mostly worth considering for mild sleep problems; mood effects are less reliable, and drug interactions matter.

L-tryptophan is an essential amino acid found in poultry, fish, eggs, dairy, soy, and seeds. In the brain, part of it is converted to serotonin and then melatonin, which helps explain its effects on sleep and some mood symptoms. The best-supported use is mild sleep support, especially sleep continuity; smaller trials also suggest benefit for premenstrual mood symptoms and some low mood symptoms. It is most likely to help adults with mild insomnia or cyclical mood changes who are not taking serotonergic medication.

Proven Benefits

01
Improves sleep continuity
02
Reduces premenstrual mood symptoms
03
May shorten sleep latency
04
May reduce depressive symptoms
05
May improve stress-related mood

Protocol

Amount
1-2 g
Frequency
Once daily, usually at bedtime
When
30-60 minutes before bed; take away from protein-heavy meals, as competing amino acids can reduce brain uptake.

Onset Time

30-60 min for drowsiness; 3-14 days for a steadier sleep effect.

Who Should Consider

Adults with mild trouble staying asleep
Adults who want a non-melatonin sleep option
Women with cyclical premenstrual mood symptoms
Adults with mild low mood plus poor sleep

Food Sources

  • Turkey or chicken breast (~250-300 mg per 100 g)
  • Salmon or tuna (~250-300 mg per 100 g)
  • Tofu or tempeh (~200-300 mg per 100 g)
  • Pumpkin seeds (~150-170 mg per 30 g)
  • Milk (~100 mg per 250 mL)
  • Eggs (~80-90 mg each)

How It Works

L-tryptophan enters the brain through the large neutral amino acid transporter, then is converted to 5-HTP, serotonin, and later melatonin. Raising brain tryptophan availability can modestly increase serotonergic signaling and nighttime melatonin synthesis, which may improve sleep and some mood symptoms. Protein-heavy meals can blunt this by competing for transport.

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