Which Hormone Causes Sleep?

Sleep is influenced by several hormones and neurotransmitters, and there isn’t a single hormone responsible for causing sleep. Instead, sleep is regulated by a complex interplay of various factors, including the following key hormones and neurotransmitters:

  • Melatonin: Melatonin is a hormone produced by the pineal gland in the brain. It plays a crucial role in regulating the sleep-wake cycle (circadian rhythm). Melatonin levels naturally rise in the evening, signaling to the body that it’s time to prepare for sleep. Exogenous melatonin supplements are sometimes used to help people with sleep disorders or jet lag.
  • Adenosine: Adenosine is a neurotransmitter that accumulates in the brain as you stay awake. The longer you are awake, the higher the levels of adenosine in your brain. Adenosine promotes sleepiness and the need for rest, and its levels drop when you sleep or rest.
  • Serotonin: Serotonin is a neurotransmitter that affects mood, among other things. It also plays a role in promoting wakefulness when it is converted into another neurotransmitter called norepinephrine. Low serotonin levels may contribute to sleep problems and disorders like insomnia.
  • GABA (Gamma-Aminobutyric Acid): GABA is an inhibitory neurotransmitter that helps calm brain activity and promote relaxation. It plays a significant role in sleep regulation, and medications that enhance GABA activity are sometimes used to treat sleep disorders.
  • Cortisol: Cortisol is a hormone produced by the adrenal glands, and its levels typically follow a diurnal pattern, with higher levels in the morning and lower levels in the evening. However, cortisol also plays a role in wakefulness and alertness.
  • Orexin (Hypocretin): Orexin is a neuropeptide that helps regulate wakefulness and arousal. A deficiency in orexin can result in narcolepsy, a sleep disorder characterized by sudden, uncontrollable daytime sleep attacks.

The sleep-wake cycle is regulated by the interaction and balance of these hormones and neurotransmitters. The circadian rhythm, exposure to natural light, and environmental factors also influence sleep patterns. Additionally, sleep is influenced by lifestyle choices, such as diet, physical activity, and stress management, which can affect the hormonal and neural signals that promote sleep.