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Table of Contents
- What happens to light in spring?
- Why does more light make sleep harder?
- How to sleep better when the clocks change
- Creating the right bedroom environment for spring
- Seasonal light and sleep FAQs
What happens to light in spring?
On the last Sunday in March, the clocks go forward one hour, marking the start of British Summer Time (BST). The familiar reminder is "spring forward, fall back." In practice, it means slightly darker mornings for a few weeks, and noticeably lighter evenings from that point onwards.
From late March through to the Summer Solstice on 21 June, the days continue to lengthen. Some parts of the UK experience close to 19 hours of daylight at the peak of summer. That is a dramatic shift from the short, dark days of January, and your body notices every part of it.
The key change is not just the amount of light, but when it arrives. Research published in PMC found that in summer, people receive around 23% of their daily light exposure between 6pm and midnight, compared with just 9% during autumn and winter. That shift in timing, light arriving later in the day rather than earlier, is what makes spring and summer evenings feel so different to your internal clock.
Why does more light make sleep harder?
The body does not respond to light passively. Light is the primary signal that sets and resets the circadian rhythm, the internal 24-hour clock that governs when you feel alert, when you feel sleepy, and when your body prepares for rest.
Melatonin: your body's darkness signal
Melatonin is a hormone produced by the pineal gland in the brain. Its job is to signal to the body that darkness has arrived and sleep should follow. The body begins producing melatonin in low light conditions, typically around two to three hours before natural sleep onset.
The problem with lighter evenings is straightforward: more light in the evening delays melatonin production. Research in the Journal of Pineal Research found that melatonin onset occurs close to one hour later in summer compared with winter, and sleep times shift accordingly. For most people, that means taking longer to fall asleep, even when they feel tired.
Melatonin levels are also measurably lower in spring and summer overall. The same research found that peak nocturnal melatonin concentrations are significantly higher in winter than in the lighter months. In practical terms, your body's sleep signal is both delayed and quieter from March through to September.
The circadian rhythm disruption
Beyond melatonin, the spring clock change itself creates a one-hour mismatch between the body's internal clock and the social clock. For most people, the adjustment takes several days. For those who already experience disrupted sleep or insomnia, research suggests the realignment can take considerably longer.
The effects of that disruption are not trivial. The clock change has been associated with:
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Increased irritability and difficulty concentrating in the days following the change
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Impaired cognitive function and reduced productivity
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Disrupted mood, particularly in those prone to low mood or seasonal sensitivity
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According to the BBC, a short-term increase in heart attacks, strokes and road accidents in the days after the spring change
Darker mornings add a separate complication
While lighter evenings delay sleep onset, darker mornings in the immediate weeks after the clock change make it harder to wake feeling rested. Morning light is the signal that tells the body to suppress melatonin and raise cortisol, the hormone that promotes alertness. Without it arriving at the expected time, waking up feels harder than it should.
How to sleep better when the clocks change
The good news is that the body adapts. The transition is manageable, and a few practical steps make it considerably easier. The Oxford Health Biomedical Research Centre recommends the following approach:
In the week before the clocks go forward
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Shift your bedtime gradually. Move it 15 minutes earlier each night in the three or four days before the change. By the time the clocks go forward, your body will be closer to the new schedule.
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Reduce caffeine and alcohol in the evenings. Both interfere with sleep onset and sleep quality, and their effects are compounded when the circadian rhythm is already under pressure.
During the adjustment period
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Get morning light as early as possible. Exposure to bright light in the morning is the fastest way to reset the circadian clock. Open the curtains as soon as you wake, or step outside briefly before starting the day.
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Keep your sleep schedule consistent. Resist the temptation to sleep in at weekends. Irregular sleep timing makes the adjustment take longer.
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Be patient. For most people, the body settles into the new rhythm within one to two weeks. If you already find sleep difficult, give yourself a little longer and avoid compounding the disruption with late nights or irregular routines.
Managing the lighter evenings
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Dim the lights in your home at least an hour before bed. Bright indoor lighting in the evening has a similar effect to outdoor light on melatonin production.
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Limit screen use in the hour before sleep. Screens emit blue-spectrum light, which is particularly effective at suppressing melatonin.
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Make your bedroom as dark as possible before you try to sleep. This is where your bedroom environment becomes important.
Creating the right bedroom environment for spring
A good sleep environment depends on three things: darkness, temperature, and comfort. Spring challenges all three. The evenings are lighter, the mornings arrive earlier, and the temperature in the bedroom starts to rise. Addressing each one makes a practical difference.
Controlling light in the bedroom
The single most effective change for spring sleep is increasing the level of darkness in the bedroom. A room that was adequately dark in January may not be dark enough in May, when early morning light arrives before 5am in many parts of the UK.
Curtains with a blackout lining are the most reliable solution. They block light at both ends of the night, helping you get off to sleep during the lighter evenings and stay asleep through the early mornings. A well-fitted silk or cotton eye mask is a simpler alternative if curtain changes are not practical.
Adjusting your bedding for spring
Light changes are not the only shift that spring brings. The temperature in the bedroom rises too, and bedding that worked well in February can leave you waking hot and unsettled by April.
The tog rating of your duvet is the most direct lever. A 13.5 tog duvet is designed for winter; sleeping under it in May is one of the most common, and most easily fixed, causes of overheating at night. Moving to a 4.5 or 7.5 tog for spring and summer allows the body's natural temperature drop during sleep to proceed without interference.
Fabric matters as much as tog. Cotton percale sheets have a crisp, open weave that allows warm air to move away from the skin rather than trapping it. If you tend to sleep warm, percale is a more comfortable choice than sateen through the lighter months. Our spring duvet covers and spring duvets are chosen with exactly this in mind.
Spring temperatures are not always reliable, though. A layered approach, a lighter duvet with a cotton throw at the foot of the bed, gives you the flexibility to adjust through the night without fully waking. It is a more responsive setup than a single heavy duvet you either keep on or kick off entirely.
For a fuller guide to preparing your bedroom for spring, including bedding choices and room temperature, we have covered the practical steps in detail.
Seasonal light and sleep FAQs
Does the spring clock change really affect sleep?
Yes, and the effects are measurable rather than anecdotal. The one-hour shift forward creates a mismatch between the body's internal clock and the new social clock. Research consistently shows that sleep onset and wake times shift by around 35 minutes to an hour in the days following the spring change, with the adjustment taking longer for people who naturally sleep late or who already experience sleep difficulties. The associated effects, including irritability, reduced concentration, and disrupted mood, are well documented.
How long does it take to adjust to the clocks going forward?
For most people, the body settles into the new rhythm within one to two weeks. Those who prepare in advance by gradually shifting their bedtime, and who get morning light exposure consistently during the adjustment period, tend to adapt more quickly. If you already experience insomnia or disrupted sleep, allow a little longer and keep your routine as consistent as possible.
Do the clocks going back in October also affect sleep?
The autumn change, when the clocks go back one hour on the last Sunday in October, is generally considered less disruptive than the spring change. Gaining an hour is easier for the body to absorb than losing one. However, the shift to shorter, darker days in autumn has been associated with an increased risk of depressive episodes and low mood, particularly for those sensitive to changes in light exposure.
Why do the clocks change at all?
Daylight Saving Time was introduced in 1916 during the First World War, initially by Germany, to make better use of available daylight. The UK followed shortly after. The practice has been debated ever since. The European Parliament voted to end DST in 2021, but no final decision has been reached, and the clock change continues for now.
What bedding is best for sleeping in spring?
A lighter tog duvet, 4.5 to 7.5 tog depending on how warm your bedroom runs, combined with cotton percale sheets, is the most practical setup for spring. Percale has a crisper, more open weave than sateen, which means it breathes better and feels cooler against the skin. Layering with a lightweight throw at the foot of the bed gives you the flexibility to adjust through the night without fully waking. Our spring bedding range is a good starting point.
Can better bedding help with sleep disruption caused by light changes?
Directly, no. Bedding cannot block light or reset your melatonin cycle. But it can remove one of the other common causes of disrupted sleep during spring: overheating. If the bedroom is warmer, the evenings are lighter, and the circadian rhythm is already under pressure from the clock change, sleeping under the wrong duvet adds unnecessary difficulty. Removing that variable, by switching to a lighter tog and a breathable fabric, means one less thing working against a settled night.
