Biochemistry of Sleep

Biochemistry is the study of the chemistry of life or the science concerned with the chemical nature and chemical behaviour of living matter.

Sleep is a dynamic process which involves continuing brain activity which acts to produce and release hormones and proteins essential for organ system regulation as well as growth as tissue repair.

hormones responsible for sleep/ Neurotransmitters

Hormones are specific molecules that acts as a chemical messenger in the endocrine system, they are produced by specific organs and glands and secreted into the blood or other body fluid (Regina, 2017).

Neurotransmitters also known as chemical messengers, are endogenous chemicals that enable transmission. They transmit signals across a chemical synapse such as a neuromuscular junction, from one neuron (nerve cell) to another target neuron, muscle cell, or gland cell (Lodish et al., 2000).

At the heart of any good night’s sleep is a healthy balanced in hormones and neurotransmitters.

Role of Serotonin in Sleep


Serotonin is one of the most important brain chemicals, or neurotransmitters, for regulating the sleep/wake cycle. Diets high in amino acid tryptophan can maintain healthy serotonin levels, but lifestyle choices like constant travel and erratic sleep schedules can disrupt its production. When serotonin levels are high its associated with wakefulness and lower levels with sleep. When the levels are not normal, sleep disturbance and other issues can result which include depression and chronic fatigue syndrome. Serotonin is synthesized by the pineal gland to make melatonin, the hormone that is directly related to healthy sleep (Ryan Hurd, 2011).

Role of Melatonin in Sleep

Melatonin is a hormone that is produced by the pineal gland in animal by the conversion of serotonin and it regulates sleep and wakefulness (Hardeland et al., 2006). In animal, melatonin is involved in the entrainment of girealian rhythm including sleep-wake timing, blood pressure regulation etc. (Alturn and Ugur, 2007). Melatonin is a hormone that is key to sleep and sleep-wake cycle in human (Delersynder et al., 2003). During the day and under the sun the pineal gland is inactive but when the sun goes down and darkness occur, the pineal gland is timed on by suprachiasmatic nucleus (SCN) and begin to actively produce melatonin which is released into the blood and winds the body down to a more lethargic and sleep-ready state.

Melatonin biosynthesis- sourse: Wikipedia (here)

Role of Norepinephrine in sleep

Norepinephrine (NE) is one of the main neurotransmitters involved in arousal, they are highly active during wake and slow firing during non-REM sleep and almost completely inactive during REM sleep (Aston and Bloom, 2009). Norepinephrine is an existing neurotransmitter which also play a role in cataplexy. Cataplexy is a component of narcolepsy in which patient experience disrupt transitions from waking into a state akin to REM sleep with complete muscle Atonia. The attack can be triggered by extreme emotion. A1AR antagonism exacerbates cataplexy as measured both by the number of attacks and duration of the attack.

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  • Rajdeep Janorkar

    Biochemistry of Sleep 5 months ago