A Sleep Hygiene Guide to Ending Sleepless Nights - The Causes of Insomnia and What the Science Supports

The Reality of Insomnia - A Modern Condition Affecting One in Five

An estimated 20% or so of people in Japan live with symptoms of insomnia. Insomnia is not merely a problem of "not being able to sleep." It leads to reduced concentration during the day, fatigue, low mood, weakened immune function, and even a higher risk of high blood pressure, diabetes, and depression. Research from the 2010s also indicates that chronic sleep loss interferes with the clearance of amyloid beta, a protein implicated in Alzheimer's disease, that accumulates in the brain.

The causes of insomnia are wide-ranging, but broadly they fall into four groups: behavioral habits that interfere with sleep, psychological factors such as stress and anxiety, physical factors (pain, frequent nighttime urination, sleep apnea), and environmental factors (light, sound, temperature). In most cases these are tangled together.

Identifying the Four Types of Insomnia

Difficulty Falling Asleep - Trouble Getting to Sleep

This applies when you cannot fall asleep for 30 minutes or more after getting into bed, three or more nights a week, for three months or longer. The most common cause is conditioned arousal. As you repeat behaviors such as looking at your smartphone in bed, turning things over in your mind, or feeling anxious about not sleeping, the brain learns that "bed equals a place to be awake."

Nighttime Awakenings - Waking Repeatedly During the Night

You wake two or more times after falling asleep and it takes 20 minutes or more to get back to sleep. This type increases with age and is common from the fifties onward. Causes include a decline in deep sleep (slow-wave sleep), frequent nighttime urination, sleep apnea syndrome, and the effects of alcohol. Alcohol promotes sleep onset, but in the process of being metabolized it produces acetaldehyde, which has a stimulant effect and makes the latter half of sleep shallower.

Early-Morning Awakening - Waking Two or More Hours Ahead of Schedule

You wake two or more hours before your intended rise time and cannot get back to sleep. This can appear as an early symptom of depression, and if it comes with low mood or loss of motivation, consider seeing a psychiatrist. In older adults it is often caused by an advance of the body clock (phase advance).

Nonrestorative Sleep - Sleeping and Still Not Rested

Your sleep time is sufficient, yet you feel no sense of having slept soundly when you get up in the morning. This is a state in which the quality of sleep, meaning the proportion of deep sleep, has dropped. Common causes are sleep apnea syndrome, periodic limb movement disorder, and overactivity of the sympathetic nervous system due to stress.

Concrete Rules of Sleep Hygiene

Managing Light Matters Most

The human body clock is reset by light. Get sunlight within 30 minutes of waking up (even on a cloudy day, outdoor light is more than ten times as bright as indoor lighting). This resets the body clock, and melatonin secretion begins roughly 14 to 16 hours later. Conversely, avoid strong light containing blue light from two hours before bed. Experiments have confirmed that continued exposure to bright screens at night suppresses melatonin secretion and pushes the time at which sleepiness arrives later.

Optimizing the Bedroom Environment

A room temperature of 18 to 20 degrees Celsius and humidity of 40 to 60% are ideal. Because people feel sleepy as their core body temperature falls, a bedroom that is too warm gets in the way of falling asleep. Block outside light with blackout curtains, and reduce noise with earplugs or a white noise machine. Use the bed for nothing but sleep and sex. Do your reading, television watching, and smartphone use somewhere other than the bed.

Limiting Caffeine and Alcohol

The half-life of caffeine is roughly 5 to 6 hours. If you drink coffee at 2 PM, half of that caffeine is still in your body at 8 PM. Avoiding caffeine after 2 PM is the safe course. Alcohol, as noted above, encourages sleep onset but markedly degrades sleep quality. A nightcap is not a solution to insomnia; it is a factor that makes it worse.

Cognitive Behavioral Therapy (CBT-I) - First-Line Treatment for Insomnia

CBT-I (Cognitive Behavioral Therapy for Insomnia) is cognitive behavioral therapy directed at insomnia. Both the American Academy of Sleep Medicine and the European Sleep Research Society recommend CBT-I as the first-line treatment for chronic insomnia. Unlike sleeping pills, its effects tend to persist after treatment ends, and there is less concern about the kind of side effects that come with medication. Note, however, that in the period when you begin the sleep restriction described below, daytime sleepiness can temporarily grow stronger.

Sleep Restriction

This is the core technique of CBT-I. First keep a sleep diary for a week and calculate the time you are actually asleep (sleep efficiency). For example, if you spend 8 hours in bed and are actually asleep for 5 of them, your sleep efficiency is 62.5%. Next, restrict your time in bed to your actual sleep time plus 30 minutes (5.5 hours in this example). Once sleep efficiency exceeds 85%, extend the time in bed by 15 minutes at a time. This strengthens the link between bed and sleep, and sleep onset improves.

Stimulus Control

If you cannot fall asleep within 20 minutes of getting into bed, get out of bed and do something boring in another room (reading under dim light, for instance). Return to bed when you feel sleepy. Repeating this rebuilds the conditioning that "bed equals a place to sleep."

Types of Sleeping Pills and the Risk of Dependence

Sleeping pills fall broadly into four categories. Benzodiazepines (triazolam, nitrazepam, and others) are strongly effective but also highly habit-forming, and long-term use is not recommended. Non-benzodiazepines (zolpidem, eszopiclone, and others) have somewhat lower dependence potential, but not zero. Melatonin receptor agonists (ramelteon) are held to be less likely to produce dependence and to have a high safety profile, though their effect is mild. Orexin receptor antagonists (suvorexant, lemborexant) are a newer class that blocks orexin, the substance that maintains wakefulness; dependence potential is low and the sleep produced is closer to natural sleep.

With any sleeping pill, the principle is to use it alongside CBT-I and to aim at tapering and stopping once symptoms improve. Treatment that relies on sleeping pills alone does not resolve the underlying problem.

Using Melatonin Correctly

Melatonin is a hormone that adjusts the body clock. In Japan, melatonin is handled as a pharmaceutical and is not sold over the counter as a supplement. In treating insomnia, a prescription drug that acts on melatonin receptors (ramelteon) is used. In some countries abroad it is available as a supplement, where the usual approach is a small dose of about 0.5 to 3 mg taken 1 to 2 hours before bed. It is not the kind of substance that works more strongly if you increase the amount. Since it does not deepen sleep but moves the hands of the body clock, it suits clearing jet lag and people whose rhythm has shifted later (night owls who cannot get up in the morning).

When to See a Doctor

If practicing sleep hygiene for 2 to 4 weeks brings no improvement, see a sleep clinic or a psychiatrist. In particular, if you have snoring together with strong daytime sleepiness you should be tested for sleep apnea syndrome, and if low mood accompanies the insomnia you should be screened for depression. Insomnia is not something to be cured by willpower; it is a medical condition that can improve with appropriate treatment. At the stage where you are still hesitating over whether to go, knowing your treatment options from a guide to insomnia makes it easier to take that first step.