Regulating glucose in the blood. Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the pancreas that regulates glucose levels in the blood.egulating glucose in the blood. Glucose is needed by cells for respiration. It is important that the concentration of glucose in the blood is maintained at a constant level. Insulin is a hormone produced by the pancreas that regulates glucose levels in the blood.
1 Snooze Foods and Pick-Me-Ups Certain foods contain an amino acid called tryptophan that causes sleepiness. 2  Carbohydrates make tryptophan more available to the brain, which is why carbohydrate-heavy meals can make you drowsy. It is made in the brain by converting tryptophan first to serotonin and then to melatonin, which is secreted at night by the pineal gland in the brain to induce and maintain sleep. 2  Scientific evidence shows little or no benefit of melatonin in improving sleep.
Plants such as coffee, tea and cacao contain caffeine. Caffeine stimulates the central nervous system promoting wakefulness by competing for adenosine receptors. Adenosine is produced by the body to promote sleep and constrict blood vessels to allow more oxygen into the brain during sleep.