Sleep problems and your blood

To be clear from the start: most sleep problems are caused by habits, tension or circumstances. Think of irregular bedtimes, worrying, caffeine or alcohol in the evening, heavy screen use or a demanding phase of life. Those causes do not show in a blood value, and that is also where the solution starts.

For sleep problems, a blood test has a modest but clear role. It can reveal physical factors that can make poor sleep worse, such as low iron stores or an overactive thyroid. An abnormal value can fit your symptoms, but does not automatically explain them. And a normal result is an answer too: you then know the search should focus on behaviour and environment.

Some people with sleep problems lie awake because of restless legs: an unpleasant, crawling feeling that flares up at rest in the evening and disturbs falling asleep. This complaint has been linked to the body's iron stores.

Ferritin reflects those iron stores and can already be low before anaemia develops. A low ferritin can be associated with restless legs and with daytime tiredness. If you recognise this picture, measuring beats guessing. The result does depend on context, such as recent illness or inflammation; our doctor weighs that in the written explanation.

An overactive thyroid drives the body on. This can show as restlessness, palpitations, sweating, weight loss and poor sleep. TSH is the first measurement to assess thyroid function; together with free T4 it shows whether the thyroid is running fast, slow or normal.

The stress hormone cortisol follows a daily rhythm: higher in the morning, falling towards the evening. With prolonged tension that rhythm can become disturbed, which can make falling asleep harder. One caveat belongs here: cortisol fluctuates from moment to moment, and a single measurement is of limited value on its own. It is useful as part of the wider picture, not as a standalone verdict on your stress level.

A vitamin D deficiency is common in the Netherlands, especially in winter. It can be associated with daytime tiredness, and someone who is exhausted during the day also finds it harder to wind down in the evening. In that way a deficiency can contribute to sleep problems indirectly.

For the sleep rhythm itself, other factors usually weigh more than a blood value: daylight in the morning, fixed times for getting up and going to bed, exercise during the day, and less screen use late in the evening. A vitamin D measurement complements that foundation; it does not replace it.

Blood testing without a referral is meant to map the physical side. You choose which values are measured, you arrange the request online and you receive your result with an explanation from a BIG-registered doctor. That way you know whether your iron stores, thyroid function or vitamin D play a part, after which you can focus on sleep habits, rhythm and relaxation.