Feeling sleepy and sluggish in the middle of winter? You're not alone. We ask two sleep experts whether you really need more slumber on colder, shorter days.
When the alarm rings in the morning and it's still pitch dark and cold outside, many of us find it hard to get out of bed. Over the long winter months, feeling weary and finding it hard to stay energised seem to be regular complaints for lots of us. Factors such as temperature and the amount of light we receive during the day in this season may play an important role.
When it's cold outside
When the temperature rises in the summer, sleeping gets challenging as we toss and turn in the sheets and fight to keep the suffocating heat at bay. Our body actually needs to cool down for us to fall asleep, so being in a colder environment can be helpful.
"Does this mean that colder weather makes us feel sleepier? Not necessarily - being uncomfortably cold can be an obstacle too," says sleep expert Dr Sophie Bostock from Sleepio.
"The optimal temperature to sleep in is around 18°C, so cooler than typical room temperature. This means it's often easier to get good-quality sleep in winter than on humid summer nights, just so long as you avoid having the heating on too high."
But winter can also make it more challenging to set up the right environment for rest.
"In winter, you get cold during the day, you put the heater on at full capacity in the house, and you may add extra duvets to your bed. This can affect your body's cooling system and you may end up struggling to fall asleep, to maintain deep sleep and thus to feel alert during the day," explains Newcastle-based neurologist and sleep expert Dr Kirstie Anderson.
Experts agree that it's actually much more likely that our need to sleep more in winter is associated with the amount of light we are exposed to. The link between our internal body clock that drives our sleep-wake cycle and light has indeed been well established. Also referred to as 'circadian rhythm', this 'clock' is controlled by a brain region known as hypothalamus, and alternates between sleepiness and alertness at regular intervals.
Lower light intensity means it's time for bed, sending a signal to the brain that it should start preparing the body for sleep. While more light is associated with alertness.
When the brain receives little light, such as in the evening, the brain responds by sending a signal to the body to produce melatonin, the 'sleep hormone', which gets your body tired and ready for bed.
In winter, the nights are longer and we get less light throughout the day and at lower intensity. This limited light exposure helps explain why we may feel like we are more tired and need more sleep. The brain doesn't get the same signal to stay awake and alert as it does in summer during the day.
"Even if you are sitting at work and getting artificial light all day, the intensity of this light is much lower than that of natural light. Even when it's grey and rainy, you will get more light intensity outside in the middle of the day, than inside in the office. The problem is that people don't go out as much and seek that natural light in winter," says Anderson.
It's also worth noting that the lower levels of light seen in winter have been linked to the seasonal affective disorder (SAD), a form of mild-to-moderate depression that arises at this time of the year. People who are affected typically experience lower energy levels and poor mood but also sleep problems.
Improving your sleep in winter
So what can you do avoid feeling sleepy during the day in winter and improve your sleep quality? Working on those two factors - light and temperature - can make a massive difference.
Think dark, cool, quiet
"The bedroom should be dark, cool and quiet, with a light exposure contrasting as much as possible with outside light. Avoid screens with artificial light," Anderson points out.
Go for a walk
Going for a walk outdoors to get natural light every day, even if it's rainy and foggy, can also help to maintain your energy levels. You can also try using a lightbox when you wake up to kick-start your circadian rhythm. As far as possible, it's also a good idea to maintain the same bedtime and wake-up time.
Ditch the booze
In winter, one of the biggest threats to sleep is actually associated with the festive season and the fact that people go to bed at irregular times and consume more alcohol.
"There's more pressure to drink in the winter because of all these parties. Though in the short term alcohol behaves like a sedative, the quality of the sleep is disrupted. It leaves us a bit more irritable and not as productive and alert. So it's all about being moderate, to deal better with this time of the year and improve our sleep," concludes Bostock.
See your GP if you're concerned
Remember that if you are suffering from chronic sleep problems such as insomnia, it's important that beyond these lifestyle changes, you speak directly with your GP who can support you. They can potentially refer you to a sleep expert or suggest effective strategies, such as cognitive behavioural therapy, the gold standard for help with better sleep.