Munching on a banana at bedtime can improve the quality of your sleep. The minerals and amino acids in a banana, like tryptophan, help relax the body. (Section A) Pairing your evening banana with other sleep-inducing foods and activities can also potentiate (enhance) the sleep restorative benefits. (Section B). The Science strongly substantiates these claims. (Section C) To read the H.M. Institute’s general Deep Restorative Sleep Protocol, click here.
Potassium and Sleep
Bananas are packed with potassium, a mineral that serves as a muscle relaxant, which can help your body feel ready to fall asleep. One large banana contains 487 milligrams of potassium, roughly 10 percent of the adequate intake of this mineral for adults.
Source of Magnesium
Another valuable mineral prevalent in bananas is magnesium. Like potassium, magnesium helps relax your muscles, making magnesium-rich foods valuable as sleep aids. One large banana has 37 milligrams of magnesium. This amount accounts for about 12 percent of the adequate intake for women and about 9 percent for men.
Sleepy Tryptophan and Melatonin
Bananas also contain tryptophan, an amino acid that’s valuable in your effort to get to sleep. Tryptophan converts to serotonin, a sleep-promoting neurotransmitter. The fruit is also a source of melatonin, which is often known as the “sleep hormone.”
In a small study of adults, blood levels of melatonin rose significantly about two hours after eating a banana, according to research published in the Journal of Pineal Research. (Source) (See below) As melatonin levels increase, you begin to feel drowsy, which may help you fall asleep.
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“Melatonin is a naturally occurring molecule biosynthesized by the pineal gland of vertebrates; it also has been identified in many plants. It is considered an important antioxidant and may retard the development of some neurodegenerative diseases and cancer. Previous studies in humans have measured melatonin metabolites in urine and have indicated that melatonin-containing foods may provide dietary melatonin. This study tested whether the consumption of fruits or fruit juice containing melatonin would influence the serum melatonin concentration and antioxidant status. In this crossover study, 12 healthy male volunteers took either juice extracted from one kilogram of orange or pineapple or two whole bananas, with a 1-wk washout period between the fruit or fruit juices. An enzyme-linked immunosorbent (ELISA) assay was used to determine the serum melatonin concentration. Serum antioxidant capacity was determined by ferric reducing antioxidant power (FRAP) assay and oxygen radical antioxidant capacity (ORAC) assay. The highest serum melatonin concentration was observed at 120 min after fruit consumption, and compared with before consumption levels, their values were significantly increased for pineapple (146 versus 48 pg/mL P = 0.002), orange (151 versus 40 pg/mL, P = 0.005), and banana (140 versus 32 pg/mL, P = 0.008), respectively. Serum antioxidant capacity following fruit consumption also significantly increased in both the FRAP (7-14% increase, P ≤ 0.004) and ORAC (6-9% increase, P = 0.002) assays. Both the serum FRAP and ORAC values strongly correlated with serum melatonin concentration for all three fruits. These findings suggest that tropical fruit consumption increases the serum melatonin concentrations and also raises the antioxidant capacity in the serum of healthy volunteers in proportion to serum melatonin levels.
J Pineal Res. 2013 Aug;55(1):58-64. .
Serum melatonin levels and antioxidant capacities after consumption of pineapple, orange, or banana by healthy male volunteers.