Why do I sleep badly: what a normal night looks like, what keeps you awake and what a sleep scan measures

In this article you read what sits behind the question why do I sleep badly: what a normal night looks like, how many people sleep badly, which habits make a night measurably shorter or more restless, and what a sleep scan does and does not see. That matters, because part of what feels wrong at three in the morning belongs to an ordinary night, while part of what feels ordinary, the afternoon coffee, the glass before bed, the last hour on a screen, measurably takes away from your sleep. The BioProfile sleep scan measures how much of these complaints you carry with you and gives you an indication of where you stand today in this area, as one of the 11 areas the full scan assesses. This is not a diagnosis. It is insight, to see where you stand today, and to help you make better choices in your food and your lifestyle. What this scan does not do: point to a cause or name a disease. That last one is work for a doctor.

How many people sleep badly

In the Dutch population aged 12 and over, more than one in four report sleep problems: trouble falling asleep, trouble staying asleep or waking too early. By sex that is 31% of women against 21% of men; by age it is lowest between 12 and 17 years (22%) and highest between 50 and 64 years (29%).⁠¹ So the question why do I sleep so badly is asked in large company, and it peaks in the busy middle years.

Worldwide, a systematic review of 18 studies with 262,582 participants estimated 852,325,091 adults with insomnia, a prevalence of 16.2%, and 414,967,941 adults with severe insomnia, 7.9%. In every age group insomnia was more common in the female sex than in the male, and only 31 of the 237 recognised countries and territories had a usable national estimate of their own.⁠⁴ Put simply: poor sleep is counted in hundreds of millions, and most countries still have no solid number.

A pooled analysis of more than 1.1 million people from the Netherlands, the United Kingdom and the United States found that one in four slept less than the recommendation for that age; among young people that was true for more than half. In adults aged 18 and older, poor sleep quality (13.3%) and insomnia complaints (9.6% to 19.4%) were more common than a short sleep duration.⁠⁵ That last line is the useful one: more people sleep badly than sleep short, so hours in bed answer only half the question. What a run of short nights does over time is in what short nights do.

What a normal night looks like

Most adults sleep between 7 and 9 hours a night, older adults 7 or 8 hours. Waking briefly, 3 or 4 times a night, is normal. Falling asleep in 10 minutes is normal, 30 minutes is normal too, and at an older age 60 minutes is still normal.⁠² In other words: lying awake for half an hour, or surfacing between three and four in the morning and turning over, is an ordinary night. It becomes a complaint when the lying awake keeps up and the next day carries it too.

Why do I sleep badly: what keeps you awake

Thuisarts lists the usual causes together: stress and worrying, the phone in the evening, irregular bedtimes, sleeping during the day, coffee and alcohol, anxiety and depression, pain, coughing, heartburn, restless legs, sleep apnoea and narcolepsy.⁠² Three of these are measured up close.

First, coffee. Even 1 or 2 cups make the quality of your sleep worse, even when you drink them 6 hours before going to sleep.⁠² A meta-analysis of 24 studies into the night after caffeine found 45 minutes less total sleep time, 7% lower sleep efficiency, 9 minutes longer to fall asleep and 12 minutes longer lying awake after falling asleep; light sleep (N1) rose by 6.1 minutes while deep sleep (N3 and N4) fell by 11.4 minutes. To keep total sleep time whole, coffee (107 mg caffeine per 250 mL) belongs at least 8.8 hours before bedtime, and a standard serving of a pre-workout supplement (217.5 mg caffeine) at least 13.2 hours before it.⁠³ In practice that puts the last coffee of the day in the early afternoon.

Then alcohol. In a laboratory study, 30 participants drank a glass an hour before bed, three consecutive nights per block, with a target value of 0.08 mg/L breath alcohol and polysomnography every night. Across all three nights alcohol raised the rate at which deep sleep built up and lowered the rate of REM sleep at the start of each night; across the block total deep sleep stayed the same while total REM sleep went down.⁠⁶ So a glass before bed can let you fall asleep faster, while the shape of the night changes under the surface.

Then screens. In the Dutch overview from 2019, 22% of children aged 8 to 13 used a screen every evening, against 83% of young people aged 13 to 18. Daily or lengthy screen use went together with up to 40 minutes less sleep per night, and young people on a screen in the hour before bed reported taking longer to fall asleep, sleeping less and waking more often during the night; in experiments, a week without evening screens, or orange glasses against blue light, reduced those complaints.⁠⁷ The hour before bed is the hour that keeps coming back in the figures.

Sleep and mood

A latent class analysis of 2,224 people with probable insomnia in the Nederlandse Slaapregister found five subtypes: highly distressed; moderately distressed but reward sensitive; moderately distressed and reward insensitive; slightly distressed with high reactivity; slightly distressed with low reactivity. The five were confirmed in a second cohort of 251 participants, and a subtype stayed the same with a probability of 0.87 over 4.8 years. Between the subtypes the risk of depression differed up to fivefold, alongside differences in life history, electroencephalogram biomarkers and course over time.⁠⁸ In plain words: two people with the same number of bad nights can sit in very different groups, and the difference lies more in temperament and life history than in the hours.

The direction over time has been pooled too. In 34 prospective cohort studies with 172,077 participants and an average follow-up of 60.4 months, the relative risk of depression in people with insomnia was 2.27, 95% confidence interval 1.89 to 2.71. The spread between the cohorts was large (I2 = 92.6%), and the correction for publication bias left the combined estimate the same.⁠⁹ For a reader that means: sleeping badly and a later low mood run together, with large variation between the studies behind the number.

Sleep during the menopause

In the SWAN study, 3,045 women aged 42 to 52 at the start were followed with 7 annual rounds. The chance of trouble falling asleep and of trouble staying asleep rose during the menopausal transition, while waking early in the morning fell from late perimenopause to postmenopause. More frequent vasomotor symptoms went together with a higher chance of all three sleep difficulties, and falling estradiol with rising FSH predicted sleep problems.⁠¹⁰ For a reader in those years: changing nights are a documented part of the transition, and the hormones followed there were estradiol and FSH.

What a sleep scan measures and what the scan leaves open

The sleep scan asks a short set of questions about the past two weeks: how you fall asleep, how the night holds up, how rested you wake, how much the next day carries it. The answers become a sleep score with the reading band the score falls in. What you get is a picture of how much of the complaint you carry, plus a starting value to measure against in two weeks.

A set of questions cannot point to a cause. Stress, a late coffee, alcohol, a screen at midnight, a low mood, pain, coughing, restless legs and sleep apnoea can all read the same in a questionnaire.⁠² It is not a diagnosis. If you also wake up tired after a full night, that is a question of its own: see why you wake up tired.

For the GP, Thuisarts gives a clear route: keep a sleep diary for 1 week and then make an appointment with the GP to talk about the sleep problem. The same page names anxiety and depression, pain, coughing, heartburn, restless legs, sleep apnoea and narcolepsy among the causes a doctor weighs up.⁠²

In summary

Sleeping badly is common: well over one in four people in the Netherlands aged 12 and over report it, most often in the years between 50 and 64.⁠¹ A normal night counts 7 to 9 hours and a handful of brief times awake, so waking in the small hours is part of the pattern.⁠² Caffeine, alcohol and the hour on a screen before bed each make the night measurably shorter or different in shape.⁠³ Insomnia comes in clearly different subtypes and runs together with a higher later risk of depression.⁠^8,9 A sleep scan gives you a number for how much of all this you carry with you, and a starting value to compare against. It is not a diagnosis, and a cause is named by a doctor.