Why is it so much harder to wake up in the morning without daylight? Not only is sunlight more inspiring to wake up to in the morning, but it signals to your brain that it’s time to get moving. The mechanism that controls feeling awake and sleepy is called circadian rhythm, or chronobiological rhythm, and this is influenced primarily by daylight. While blackout curtains in the bedroom can be helpful for sleeping in, you might want to think twice about getting them if you have trouble waking up. Daylight is a physiological stimulant for the visual system and circadian rhythm, so it can help boost your energy to start your day right.

woman lying in bedThe idea behind British Summertime (or Daylight Savings Time [DST] in the US) is to make the most of the hours of sunlight during the summer months by advancing the clock by an hour. It was first put into place during World War I and has since been credited with aiding productivity in the evenings, reducing the number of road accidents in the mornings and saving energy.

But what effect does this have on your sleep? When the clocks go forward, many find it hard to adjust to the time change. Although it is only an hour, it can take weeks for some people to get back into their routine and feel normal again

That’s because the onset of sleep is triggered by an increase in the production of the hormone melatonin – something we have less of in summer!  It is this hormone that helps to regulate the body’s circadian rhythm and promotes restful sleep.

Melatonin is produced in the evening to help us sleep and the lighter nights suppress its’ production. Low amounts of ambient light (such as that given off by radio alarm clocks, mobile phones and laptops) also have the same effect.  It is therefore important to keep the bedroom as dark as possible to encourage this production.

If ‘light’ does stops you from dropping off to sleep, or wakes you up earlier, try using an eye mask, thicker curtains or blackout blinds to block it out.

 Daylight, Sleep Patterns and Productivity

woman working in cubicleIf working inside for long periods with no sunlight makes you feel tired, you’re not alone. Daylight exposure during the day is essential for alertness and functionality, and it can significantly influence work productivity. In fact, it has been ranked as one of the top 10 most important factors to a quality work environment. Daylight can even affect work attitudes and experiences. In a 2014 study which compared the health of workers in offices with and without windows revealed that limited daylight exposure during the day can result in reduced vitality, reduced sleep quality, and physical problems.

How can individuals protect themselves from the problems associated with a lack of daylight exposure? The bigger picture solution includes improved office architecture that increases daylight in indoor work areas. Two simple remedies to increase exposure for the average office worker are (1) taking a walk during a break, and (2) enjoying lunch outdo

There are a couple days of the year where timekeeping standards affect circadian rhythm, and those are the days transitioning in and out of daylight savings time (DST). The loss or gain of an hour is enough to affect our circadian rhythm.

During the switch to standard time, where we gain an hour, most people end up getting more sleep and are not affected negatively – but not all; I personally find it harder to stand so many hours of darkness and want to sleep earlier than is good for me as a result!  However, the loss of an hour due to the switch to DST can have some surprisingly far-reaching impacts.

On this day, people average 40 minutes less of sleep, which doesn’t sound too bad. But each year on the Monday following the switch to DST, over 2,600 more workdays than average are lost due to work injuries in the US. This reflects an increase in workplace injuries of greater severity. There is also an increase in miscarriages, heart attack risk, and suicide rates associated with the chronobiological change. Additionally, DST takes a huge toll on the economy. In US markets, it equates to a single-day loss of $31 billion.

So why do we keep using BST/DST if transitioning to it causes so many problems. There are many pros and cons of DST that consider other factors beyond health and sleep. The gains in productivity from switching to standard time are negligible, definitely not enough to outweigh the losses in life, property, and money from the switch to summer hours.

While we can’t control the time that everyone adheres to, we can control our individual sleep schedules. Getting to bed an hour early before the switch to DST is recommended. For all other days, aiming for sufficient hours of sleep per night (whatever that means for you) is your best bet to ensure maximum productivity and safety for yourself.


Sleep Disorders Related to Circadian Rhythm Disturbances

Biological clock

This category of disorders features conditions in which the sleep times have become misaligned. A patient with one of these disorders does not follow the normal night time sleep.

Delayed Sleep-Wake Phase

This disorder is a sleep pattern is characterised by an out of synch sleep pattern, e.g. sleep that is delayed by two or more hours so that a person goes to sleep later at night and sleeps later in the morning.

Advanced Sleep-Wake Phase

This issue causes people to fall asleep several hours before a normal bedtime and wake up hours earlier than most people wake in the morning.

Irregular Sleep-Wake Rhythm

This disturbed pattern are due to  a person’s circadian rhythms being so disorganized that there is no clear sleep or wake pattern. People with this sleep disorder may sleep off and on in a series of naps over a 24-hour period.

Non-24-Hour Sleep-Wake Rhythm

Non-24 is a sleep disorder that causes a person’s sleep time to shift a little later every day, with the likelihood that their sleep times can go in and out of alignment with other people over time.

Shift Work

A non-traditional work schedule involving shifts that occur when most people are sleep can cause shift work disorder. The condition causes your sleep to be poor and consistent feelings of fatigue or exhaustion.

Jet Lag

Jet lag occurs when you travel across multiple time zones and have difficulty adjusting to the new schedule.


Sources: Sleep Education, Somnology, Sleep Council