Sleep as a Clinical Variable, Not a Lifestyle Afterthought

Clinicians measure blood pressure at almost every visit and weigh patients routinely, yet many never ask how their patients sleep. When they do, the question is often an afterthought at the end of a consultation, and the answer, “not great”, rarely changes the plan. This is a missed opportunity of considerable size. Sleep influences nearly every system in the functional medicine matrix, sleep disorders are among the most common undiagnosed conditions in adult practice, and improving sleep is one of the few interventions that reliably improves several problems at once.

What happens during sleep

Sleep is not a uniform state. Across a night, the brain cycles through distinct stages roughly every 90 minutes.

• Non rapid eye movement sleep progresses from light sleep to deep, slow wave sleep, which predominates in the first half of the night. Slow wave sleep is associated with physical restoration, growth hormone release, memory consolidation and, according to animal research, enhanced clearance of metabolic waste from the brain.
• Rapid eye movement sleep predominates in the second half of the night and is associated with dreaming, emotional processing and certain forms of memory.

2 processes govern when we sleep. A homeostatic drive, often called sleep pressure, builds with every waking hour and dissipates during sleep. A circadian process, driven by the central clock in the brain and synchronised by light, creates a daily rhythm of alertness and sleepiness. Good sleep occurs when these 2 processes align: high sleep pressure coinciding with the biological night. Shift work, late evening light and irregular schedules pull them apart.

How much sleep adults need

A consensus statement from American sleep medicine societies concluded that adults should regularly sleep 7 or more hours per night for optimal health, and that sleeping less is associated with adverse outcomes including weight gain, diabetes, hypertension, heart disease, depression and impaired immune function. Individual needs vary, and some people need more, but habitually sleeping less than 7 hours is common in many populations and is rarely a choice made with full knowledge of its effects.

Duration is not the only dimension. Regularity, timing, continuity and quality all matter, and research increasingly suggests that irregular sleep schedules have effects of their own.

Sleep across the matrix

In one experimental study, healthy volunteers exposed to a common cold virus were considerably more likely to develop illness if they habitually slept less than 6 hours. In others, restricting sleep for a few nights impaired glucose tolerance to a degree that would concern a clinician if seen in a patient. These are not distant associations. They are effects that appear quickly and reverse, at least partly, when sleep improves.

The disorders that are often missed

Insomnia

Chronic insomnia, meaning difficulty initiating or maintaining sleep on most nights for several months with daytime impact, is common. Cognitive behavioural therapy for insomnia is recommended as first line treatment by major clinical guidelines. It combines stimulus control, sleep restriction, cognitive techniques and sleep hygiene, and produces improvements that tend to last longer than those from sleeping tablets. Digital versions have made it more accessible.

Obstructive sleep apnoea

Repeated collapse of the upper airway during sleep causes fragmented sleep, drops in oxygen and surges in blood pressure. It is associated with hypertension, atrial fibrillation, type 2 diabetes and cardiovascular disease, and it is frequently undiagnosed. Clues include loud snoring, witnessed pauses in breathing, waking unrefreshed, daytime sleepiness, morning headaches, nocturia and resistant hypertension. Simple screening questionnaires such as STOP Bang help identify who should be referred for a sleep study. Central weight gain increases risk, but slim people can have sleep apnoea too.

Restless legs syndrome

An urge to move the legs, usually with uncomfortable sensations, worse in the evening and relieved by movement. Iron deficiency is an important contributor, and guidelines recommend checking iron status, as treatment of low iron stores can improve symptoms. Some medicines, including certain antidepressants and antihistamines, can worsen it.

Circadian rhythm disorders

Delayed sleep phase, common in adolescents and young adults, and shift work disorder occur when the internal clock and required schedule are misaligned.

Taking a sleep history

A structured sleep history takes a few minutes and should be part of every assessment of chronic symptoms.

• What time do you go to bed, and what time do you get up, on work days and free days?
• How long does it take to fall asleep? How often do you wake, and for how long?
• Do you feel refreshed on waking? How sleepy are you during the day?
• Do you snore? Has anyone noticed pauses in your breathing?
• Do you have uncomfortable sensations or urges to move your legs in the evening?
• Do you work shifts? How much screen use and light exposure do you have in the evening?
• How much caffeine and alcohol do you have, and when?
• What medicines and supplements do you take?
• Is worry, pain, a baby, a partner or a noisy environment keeping you awake?

The difference between work day and free day sleep times is revealing. A large shift in timing on free days suggests chronic sleep restriction or circadian misalignment.

Medicines and substances that affect sleep

Many commonly used substances affect sleep and are easy to overlook. Caffeine has a long half life, so afternoon intake can affect sleep hours later. Alcohol shortens the time to fall asleep but fragments sleep in the second half of the night and worsens sleep apnoea. Some antidepressants, beta blockers, corticosteroids, decongestants and stimulants disrupt sleep. Diuretics taken late in the day cause nocturia. Sedatives can worsen sleep apnoea and cause dependence.

Improving sleep: an evidence informed approach

1. Screen for and treat sleep disorders. Refer suspected sleep apnoea for assessment, check iron in restless legs, and consider cognitive behavioural therapy for chronic insomnia.
2. Anchor the wake time. A consistent wake time, including on free days, is one of the most powerful ways to stabilise the circadian rhythm.
3. Use light deliberately. Bright light, ideally daylight, in the morning; dim light in the evening.
4. Time caffeine and alcohol. Limit caffeine to the morning where it affects sleep, and reduce evening alcohol.
5. Protect the sleep window. Allow enough time in bed for at least 7 hours of sleep where possible.
6. Address the reasons for waking. Pain, nocturia, reflux, hot flushes, anxiety and environmental noise each have specific solutions.
7. Be cautious with supplements. Melatonin has evidence for some circadian rhythm disorders and jet lag, with more modest effects in insomnia. Magnesium and herbal products have limited evidence; product quality varies.

An illustrative case

A 52 year old accountant attends for weight gain, hypertension and poor concentration. He sleeps from midnight to 6 on weekdays and until 10 at weekends, drinks 2 glasses of wine most evenings and 3 coffees in the afternoon, and his wife says he snores loudly and sometimes stops breathing. His STOP Bang score is high. His physician refers him for a sleep study, which confirms moderate obstructive sleep apnoea, and he starts treatment. Meanwhile he moves his caffeine to the morning, reduces alcohol and fixes his wake time. At 3 months his daytime concentration has improved markedly, his home blood pressure readings have fallen and he has more energy to exercise. Several problems improved because one mediator was addressed.

A vital sign in all but name

Sleep is not a lifestyle preference to be considered after the important clinical questions have been answered. It is one of the important clinical questions. Asking about it systematically, recognising the disorders that disrupt it and building it into plans is among the highest yield habits any practitioner can adopt.