Summary
In the Nordic countries, sleep problems are most common in winter. Short, dark days push the body clock later, so falling asleep and waking up both get harder.
The strongest tool is light at the right time: daylight or a light lamp in the morning, dim light in the evening. A steady wake time, enough vitamin D and a calm evening routine help too. In summer, the problem flips, and blackout curtains become your friend.
Many people in Norway, Sweden, Finland and Denmark know the pattern. From November the mornings feel heavy, the alarm feels earlier than it is, and evenings drag on with a wired, restless mind. It is not just in your head. Your internal clock is set mainly by light, and in the dark season it gets far less of the signal it needs. This guide explains what happens to sleep at high latitudes and what research suggests helps.
What the dark season does to your sleep
Insomnia peaks in winter
The Tromsø Study surveyed 8,951 adults aged 30 to 87 in Tromsø, Norway, at 69 degrees north, above the Arctic Circle. Data were collected across the seasons between October 2007 and December 2008. Significantly more people reported current sleeping problems in winter than in other seasons, and the fewest reported them in spring. Interestingly, mental distress did not differ by season, which suggests the winter effect on sleep is not simply about mood.
Your melatonin rhythm drifts later
A small study in the International Journal of Circumpolar Health followed 14 people at 69 degrees north from January to the March equinox, half of them with insomnia during the dark period. Melatonin release showed signs of shifting later during the dark period and returned to a normal night time pattern by the equinox. People with sleep problems were slower to recover, and those with higher morning melatonin felt more tired in the morning. In simple terms: without morning light, the night hormone hangs on into the day.
Your body clock is reset each morning by light. In the Nordic winter that reset arrives late and weak, so the whole night shifts later.
Vitamin D also drops
The same short days stop your skin from making vitamin D for several months. A 2018 meta analysis of nine studies with 9,397 participants found that people with vitamin D deficiency had 1.5 times the odds of sleep disorders and higher odds of short sleep. A 2022 meta analysis found vitamin D supplements improved sleep quality scores compared with placebo. Most of this evidence is observational, but it is one more reason to keep your vitamin D up in winter. Read our full guide to vitamin D in Scandinavia and the Nordics.
What helps: a Nordic winter sleep plan
1. Get light early
Morning light is the strongest signal your body clock receives. A meta analysis in Sleep Medicine Reviews (2016) pooled 53 studies with 1,154 participants and found that light therapy improved sleep problems overall (effect size g = 0.39), with somewhat larger effects for insomnia (0.47) and body clock problems (0.41). The effects were small to medium, but consistent. In practice: go outside soon after waking, even on a grey day, or sit near a light therapy lamp in the morning. If you have an eye condition or bipolar disorder, ask your doctor before using a light lamp.
2. Dim the evening
Bright screens and ceiling lights late in the evening tell your brain it is still day, which pushes sleep even later. Switch to warm, low lamps in the last hour or two before bed.
3. Keep the same wake time all week
A fixed wake time, even at weekends, gives your clock an anchor when daylight cannot. See the power of a sleep routine.
4. Keep vitamin D in range
The Nordic Nutrition Recommendations 2023 set 10 µg a day for adults and 20 µg for people aged 75 and over or with little sun exposure.
5. Calm a busy mind
Long, dark evenings can leave the mind wired. Magnesium and calming herbs are gentle options. See magnesium for sleep and lemon balm, chamomile and lavender for sleep.
And in summer, the opposite problem
Under the midnight sun, or the long light nights further south, evening light arrives when your body should be winding down. Blackout curtains or a sleep mask, and the same steady wake time, help protect your sleep from June to August.
Season by season
| Season | What happens | What helps |
|---|---|---|
| Dark season (November to January) | Little morning light; body clock drifts later; insomnia most common | Morning daylight or light lamp, fixed wake time, dim evenings |
| Late winter (February to March) | Vitamin D at its lowest; light returning quickly | Check vitamin D, spend time outside in the morning |
| Spring | Fewest sleep problems in the Tromsø Study | Keep the routine you built in winter |
| Summer (light nights) | Evening light delays sleep | Blackout curtains, eye mask, regular bedtime |
When to see a doctor
If poor sleep lasts more than a few weeks, comes with low mood that does not lift, or you snore loudly and feel very sleepy in the day, speak to your doctor. Seasonal depression and sleep apnoea need proper assessment.
Where FOOON fits
Morphéon is our melatonin free evening formula, combining magnesium glycinate, L Tryptophan, L Glycine, lemon balm, chamomile, lavender, zinc and chromium in liposomal capsules. Magnesium contributes to normal psychological function and to the reduction of tiredness and fatigue. For vitamin D, VIT & MIN + CoQ10 provides 7.5 µg of vitamin D3 per capsule. Neither replaces morning light, but both can support a good winter routine. For more on deeper rest, read how to get more deep sleep.
Frequently asked questions
Why do I sleep worse in the Scandinavian winter?
Your body clock is set mainly by morning light. In the dark season that signal is weak, so melatonin release drifts later and both falling asleep and waking up get harder. Research in Tromsø found sleep problems were most common in winter.
Do light therapy lamps help with sleep?
A meta analysis of 53 studies found light therapy improved sleep problems, especially insomnia and body clock problems, with small to medium effects. Morning use works best. Ask your doctor first if you have an eye condition or bipolar disorder.
Is vitamin D linked to sleep?
Vitamin D deficiency is associated with poorer and shorter sleep, and supplements improved sleep quality scores in a meta analysis. The evidence is mostly observational, so keeping vitamin D in range is sensible but not a cure on its own.
How do I sleep during the midnight sun?
Block evening light with blackout curtains or an eye mask, keep a regular bedtime and wake time, and avoid bright screens late in the evening.
When should I see a doctor about winter sleep problems?
If poor sleep lasts more than a few weeks, comes with persistent low mood, or you snore loudly and feel very sleepy during the day, speak to a doctor.
Bottom line
The Nordic dark season shifts your body clock later and makes sleep harder. Morning light, dim evenings, a fixed wake time and enough vitamin D are the foundation, and calming nutrients can support a better evening wind down.
Explore Morphéon →Related reading: why sleep is the foundation of health · HYPNOS
Sources
- Johnsen MT, Wynn R, Bratlid T. Is there a negative impact of winter on mental distress and sleeping problems in the subarctic: the Tromsø Study. BMC Psychiatry. 2012. doi.org/10.1186/1471-244X-12-225
- Bratlid T, Wahlund B. Alterations in serum melatonin and sleep in individuals in a sub-arctic region from winter to spring. International Journal of Circumpolar Health. 2003. doi.org/10.3402/ijch.v62i3.17561
- van Maanen A, Meijer AM, van der Heijden KB, Oort FJ. The effects of light therapy on sleep problems: A systematic review and meta-analysis. Sleep Medicine Reviews. 2016. doi.org/10.1016/j.smrv.2015.08.009
- Gao Q, Kou T, Zhuang B, Ren Y, Dong X, Wang Q. The Association between Vitamin D Deficiency and Sleep Disorders: A Systematic Review and Meta-Analysis. Nutrients. 2018. doi.org/10.3390/nu10101395
- Abboud M. Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients. 2022. doi.org/10.3390/nu14051076
- Nordic Council of Ministers. Nordic Nutrition Recommendations 2023: Vitamin D. 2023. pub.norden.org
