Poor sleep is one of the most common health complaints in the UK. Difficulty falling asleep, waking in the night, early morning waking, and unrefreshing sleep affect millions of people — yet the underlying biological causes are frequently overlooked.
While stress and lifestyle factors play an important role, hormones and neurotransmitters are central to the regulation of sleep. When these systems are disrupted, sleep quality often suffers significantly.
How the Body Regulates Sleep
Sleep is governed by two primary systems: the circadian rhythm (the body’s internal 24-hour clock) and sleep pressure (the build-up of adenosine in the brain during waking hours). Both systems are influenced by hormones and neurotransmitters.
Key Hormones That Affect Sleep
Melatonin
Melatonin is the body’s primary sleep hormone, produced by the pineal gland in response to darkness. It signals to the body that it is time to sleep. Disrupted melatonin production — caused by light exposure, stress, or ageing — can make it difficult to fall asleep and maintain a consistent sleep rhythm.
Cortisol
Cortisol follows a natural daily rhythm, peaking in the morning and declining through the day. When cortisol remains elevated in the evening — due to chronic stress, late-night screen exposure, or HPA axis dysregulation — it can suppress melatonin production and make it difficult to wind down and fall asleep.
Progesterone
Progesterone has natural sedative and calming properties, partly through its interaction with GABA receptors in the brain. Declining progesterone — as seen during the luteal phase of the menstrual cycle, perimenopause, and menopause — is a common cause of sleep disruption in women.
Oestrogen
Oestrogen influences serotonin and noradrenaline, both of which affect sleep quality. Declining oestrogen during menopause is associated with night sweats, hot flushes, and disrupted sleep architecture.
Thyroid Hormones
Both an overactive and underactive thyroid can disrupt sleep. Hyperthyroidism is associated with difficulty falling asleep and restlessness, while hypothyroidism can cause excessive sleepiness and unrefreshing sleep.
Key Neurotransmitters That Affect Sleep
GABA
GABA is the brain’s primary calming neurotransmitter and is essential for the transition into sleep. Low GABA activity is associated with difficulty falling asleep, racing thoughts at bedtime, and light, fragmented sleep.
Serotonin
Serotonin is a precursor to melatonin and plays an important role in regulating sleep-wake cycles. Low serotonin can disrupt both mood and sleep quality.
Dopamine
Dopamine influences wakefulness and arousal. Imbalances can contribute to restless sleep, difficulty switching off, and early morning waking.
The Advanced Neurotransmitter & Hormone Test measures GABA, serotonin, dopamine, and other key neurotransmitters alongside saliva hormone levels — providing a comprehensive view of the neurochemical and hormonal factors that may be disrupting sleep.
Sleep Disturbances in Women: A Hormonal Pattern
Women are disproportionately affected by sleep disturbances, and hormonal fluctuations are a significant reason why. Many women notice worsening sleep in the days before menstruation, during pregnancy, and particularly during perimenopause and menopause.
The Comprehensive Female Saliva Hormone Profile (LCMS) measures oestrogen, progesterone, testosterone, DHEA, and cortisol — helping to identify the hormonal patterns that may be contributing to sleep difficulties.
The Cortisol-Sleep Connection
Chronic stress is one of the most common drivers of sleep disruption. Elevated evening cortisol suppresses melatonin, increases arousal, and makes it difficult to transition into restful sleep. Assessing daily cortisol patterns is an important step in understanding stress-related sleep problems.
The Neurotransmitter and Cortisol Test measures daily cortisol patterns alongside key neurotransmitters — providing insight into how stress physiology may be affecting sleep quality.
Frequently Asked Questions
Can hormone imbalance cause insomnia?
Yes. Low progesterone, declining oestrogen, elevated cortisol, and thyroid imbalances can all contribute to insomnia and disrupted sleep patterns.
Does menopause cause sleep problems?
Yes. Night sweats, hot flushes, declining progesterone, and disrupted serotonin signalling during menopause are common causes of sleep disturbance in women over 40.
Can low GABA cause insomnia?
Low GABA activity is associated with difficulty falling asleep, racing thoughts at bedtime, and light, fragmented sleep. Supporting GABA activity is a common focus in addressing sleep difficulties.
Final Thoughts
Poor sleep is rarely just a lifestyle issue. The hormonal and neurochemical environment of the body plays a central role in sleep quality. Understanding your own biological profile may be a meaningful step towards identifying the root causes of sleep disturbances and finding more effective solutions.
This article is for informational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional for diagnosis and treatment.