What Happens While You Sleep, and How Breathing Problems Can Steal Your Rest

Sleep is not one continuous state. Through the night your brain moves through a repeating pattern of stages, known as sleep architecture. Each cycle lasts roughly 90 minutes, and most adults complete four to six cycles a night.

The stages of sleep

• Light sleep (N1 and N2): the transition from wakefulness. Heart rate slows and body temperature falls. N2 makes up around half of the night.

• Deep sleep (N3): the most physically restorative stage, concentrated in the first half of the night. It supports tissue repair and hormone release.

• REM sleep: the brain is highly active and most dreaming occurs, while most muscles relax. REM periods lengthen towards morning and support memory and emotional wellbeing.

How sleep-disordered breathing disrupts this

Sleep-disordered breathing ranges from snoring to obstructive sleep apnoea (OSA). As we sleep, the muscles around the throat relax. In some people the airway narrows or collapses, reducing or stopping airflow.

The brain responds with a brief awakening to reopen the airway, usually too short to remember. Repeated many times a night, this:

• fragments sleep, pulling you out of deep and REM sleep

• causes dips in oxygen levels

• leaves you unrefreshed, even after eight hours in bed

REM sleep is especially vulnerable, because muscle relaxation is greatest during this stage.

Signs to look out for

Loud snoring, pauses in breathing, gasping, morning headaches, a dry mouth on waking and daytime sleepiness.

How we can help

Dentists are often first to spot the signs. Where appropriate, we can refer you for a sleep study and, if diagnosed, discuss a custom-made oral appliance alongside your medical care.

Concerned about your sleep? Contact Whitland Dental Co on 01994 238 660 or book at www.whitlanddental.co.

References

Eckert, D. J., & Malhotra, A. (2008). Pathophysiology of adult obstructive sleep apnea. Proceedings of the American Thoracic Society, 5(2), 144–153. https://doi.org/10.1513/pats.200707-114MG

National Institute for Health and Care Excellence. (2021). Obstructive sleep apnoea/hypopnoea syndrome and obesity hypoventilation syndrome in over 16s (NICE guideline NG202). https://www.nice.org.uk/guidance/ng202

Ohayon, M. M., Carskadon, M. A., Guilleminault, C., & Vitiello, M. V. (2004). Meta-analysis of quantitative sleep parameters from childhood to old age in healthy individuals. Sleep, 27(7), 1255–1273. https://doi.org/10.1093/sleep/27.7.1255

Patel, A. K., Reddy, V., Shumway, K. R., & Araujo, J. F. (2024). Physiology, sleep stages. In StatPearls. StatPearls Publishing. https://www.ncbi.nlm.nih.gov/books/NBK526132/

Note: StatPearls chapters are updated regularly, so check the "last update" date on the page before publishing.

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