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How Does Daylight Savings Time Affect Sleep?

Mother and daughter changing the time for Daylight Savings Time

Have you ever wondered whether Daylight Savings Time has any impact on sleep?

A lot of factors influence how well you sleep – and it’s long been established that shift work and jet lag are very damaging to one’s natural sleep cycles and quality.  What about Daylight Savings?

What is Daylight Savings Time?

Daylight Savings Time (DST) is the practice of turning clocks forward by an hour during the warmer months. More than seventy countries across the globe do this – generally, those further from the equator. These include New Zealand, Australia, the USA, Canada, the United Kingdom, and parts of the European Union.

The motivation behind DST is to align waking hours with those of natural sunlight by advancing the times of sunrise and sunset.  In the middle of New Zealand’s summer, the sun rises very early in the morning. On the summer solstice (December 21st) at Standard Time, sunrise would be, depending on how far south one is, around or before 4.30 a.m. Advancing clocks by an hour enables sunrise to occur an hour later; a more convenient time to suit our nine-to-five schedules and sleep-wake cycles, and provide more daylight hours for recreation at the end of the workday.

Across New Zealand, DST commences on the last Sunday of September and Standard Time returns on the first Sunday in April.

History and Reasoning Behind Daylight Savings Time (DST)

If we lived based solely on our human circadian rhythms, our daily schedules would be naturally adjusted to sunlight. Ancient societies operated in this way. Our modern lifestyles, however, are dictated by a stringent clock-based society, and during the warmer months of the year, the hours of daylight do not sync with our “9-5” schedules.

Advancing clocks by an hour for summer dates back to the late 1700s. It was originally proposed by Benjamin Franklin to help economise on the use of candles. It wasn’t until 1908, however, that Canada became the first country to implement it. This was purely to help conserve energy. It has been more widely adopted over time since then.

DST isn’t used at all in Africa, Asia, Latin America, or the Caribbean, nor is it observed in the US states of Hawaii and Arizona (except the Navajo Nation which occupies lands across Arizona, Utah, and New Mexico).

In New Zealand, DST was first observed in 1927, with its timing altering intermittently since then. During WWII it was observed year-round as an emergency regulation. It was reintroduced in 1974-1975 and has been in its current form since 2007.


Proponents of DST state that it improves health, mental well-being, and lifestyle opportunities as it provides more “usable” daylight. It is also favoured by governments and businesses as being economically beneficial.

Contrary to common belief, DST doesn’t give us “more” daylight! All it does is shift the timing of when we are awake during daylight versus darkness. We have more daylight hours during summer and more darkness hours in winter in places like NZ due to the Earth’s seasonal tilt in relation to the sun. This is the case regardless of how our clocks are set.

DST does have some fierce opponents for being inconvenient and disruptive. Particularly, farmers do not approve of the practice, as many farming schedules are driven by the presence of dew and dairy cattle’s readiness to be milked – and these are strictly dictated by the sun. Evening entertainment interests such as fireworks, light displays, and outdoor cinemas and concerts rely on darkness – DST pushes timing for these later. Furthermore, some religious groups (e.g., observant Jews and Muslims) are required to pray or fast based on daylight hours.

DST also has definite impacts on our sleep.

The Impact of Daylight Savings Time on Sleep

The human body functions on natural sleep-wake cycles referred to as the circadian rhythm. It relies on natural light and darkness as drivers of hormones like melatonin that control alertness and sleepiness.

Standard Time better aligns with these natural cycles. 

When adjusting to a change in time zone (which that one-hour advancement when DST commences essentially is), for each 1-hour of time change, it is said to take the human body a day to adjust.

But it can take significantly longer than this.

A Sleep Science and Practice Study found that the transition to DST is strongly associated with disturbed sleep schedules. This causes an acute reduction in sleep duration and a spike in restless, poor sleep quality. These effects were reported up to a week after clocks were turned forward.

Moreover, during DST “early birds” can find it more difficult to fall asleep when the sun does not set until later – and any parent of young children will attest to this! We tend to go to bed later at night during DST, achieving less sleep overall.

Researchers have identified numerous health and safety ramifications of the annual DST transition:

  • A higher incidence of atrial fibrillation (irregular heartbeat) resulting in hospital admissions
  • An increased risk of cardiovascular events (heart attacks and strokes)
  • More emergency department admissions
  • More missed medical appointments
  • A higher incidence of traffic accidents (especially during the week following the DST transition)
  • More mood disturbances

Negative impacts of the DST transition are more likely to affect teens, shift workers, people with chronically restricted sleep during the work/school week, and anyone who struggles to sleep while the sun is up.

Adjusting to Daylight Savings Time

It should be easy to adjust to a one-hour clock change every six months, right?  Not necessarily! – Scientific data demonstrates that the transition to DST has a cumulative effect on sleep quality and duration.

Tips for the DST Transition: 

  1. Get the best quality sleep you can in the week or two before DST begins.
  2. In the fortnight before DST begins, aim to go to bed 15 -20 minutes earlier. Increase this by 15 minutes every couple of days.
  3. Don’t sleep in on the first day of DST. If you are very sleepy, take a 15-20 minute “power nap” in the early afternoon (before 3 p.m.).
  4. Try to generally go to bed and wake up at the same time each day – even at weekends! – to help your body regulate sleep.
  5. Maintain healthy sleep hygiene practices.

When clocks transition back to Standard Time in April, the extra hour of sleep we gain for a night can (at least temporarily) boost health and well-being. Standard Time in the cooler seasons supports healthier sleep schedules aligned with natural light and darkness. This demonstrably supports reduced risks of heart attack, stroke, sleep-related mood disorders and other health issues.

Sleep Better – Address Snoring & Sleep Apnea.

Actively promoting better sleep will help during the DST transition period and into the lighter summer months. If you or your sleeping partner snore (a major disruptor of sleep), using APNEARX can make a positive difference.

Reducing snoring offers the best opportunity to sleep well. It also improves cardiovascular health, mood, concentration, memory, metabolism and weight, immunity, and overall performance.

ApneaRx is the NZ brand of an extremely effective oral anti-snoring device. It is worn in the mouth while you sleep, gently moving the lower jaw slightly forward and opening the airways to help prevent or even stop snoring whilst also treating the symptoms associated with mild to moderate sleep apnea. It is suited for use by adults of all ages.  Understand how ApneaRx works and order yours now.