Reasons you're tired all the time: vitamins and more

Kathryn Fielding / 13 Dec 2017

Trouble getting out of bed in the morning now it’s cold and dark? Well, you aren’t alone. Winter tiredness is an actual thing, even the NHS recommends ways to beat it...


The question is, is it purely coincidence that winter is associated with sleepiness? Surely there more to it than red wine and log fires? Read on for real reasons why that snooze button is getting a lot of love this winter.


Melatonin, the sleep hormone which makes us feel more tired, is released continuously when it’s dark, with production inhibited only by light. An increase of melatonin levels in the blood makes us feel less alert and sleep becomes more inviting, so it’s a good job that levels are negligible during daylight hours.

So, as we get closer to the shortest day of the year (December 21) when we will be exposed to just 7hr 49min 44s of daylight (in comparison to the longest day July 21 when we enjoy 16hr 38min 18s of daylight) it’s no wonder we experience more sleepiness in the dark of winter.   

C-Reactive protein

C-reactive protein (CRP) is a stable marker of inflammation that has been shown to be a predictor of the potential risk of myocardial infarction and stroke. CRP has been found to have a significant association with sleep disorders, with poor sleep quality correlating with elevated CRP. Researchers have found that CRP has a significant seasonal variation, with higher values during winter than in summer.

Vitamin D deficiency

Vitamin D plays an important role in metabolic and immune system functions. Evidence shows that Vitamin D deficiency is associated with sleep problems, particularly daytime sleepiness. This is a major issue at this time of year as 50% of the UK’s adult population have insufficient levels of vitamin D, with 16% having a severe deficiency during winter.

Being overweight

With comfort food replacing lighter salads on menus, the associations of festive celebrations and excessive consumption, along with almost every marketing channel promoting deliciously “naughty” treats, weight gain in the winter months is often inevitable. This can cause issues with sleep as being overweight does increase the risk of fatigue, for various reasons such as the fact that carrying more weight is physically exhausting and individuals are more likely to have a condition where fatigue is a symptom, such as diabetes.

Lack of exercise

The lack of sunlight and dropping temperatures do correlate strongly with a decrease in motivation to workout. As exercise raises your heart rate, causing an adrenaline surge, regular exercise in the morning or afternoon has been shown to improve sleep quality, whilst an overall lack of exercise can cause general fatigue and daytime sleepiness.


A common presenting symptom of an infection is sleepiness. When the body is attacked by an infection it’s priority is to fight it off, which uses energy as the immune system is put to work so you may well be fighting off a problem lingering under the surface.

Click here to take our free interactive nutrition consultation to find out what could be causing your sleepiness and get expert nutrition and lifestyle advice to help you improve your energy levels