Insomnia is defined as difficulty falling asleep, staying asleep, or waking up too early, accompanied by complaints of fatigue, irritability, or decreased daytime performance.

According to the International Classification of Sleep Disorders (ICSD-3) and the DSM-5-TR, a diagnosis requires symptoms at least three times a week for three months or more, with significant functional impact. A distinction is made between:

• Insomnia of onset (difficulty falling asleep ≥ 30 min);
• Maintenance insomnia (prolonged or frequent awakenings);
• Early awakening (before the desired time, without being able to fall back asleep).

Many cases combine several patterns, evolving into chronic insomnia if left untreated.

Why does insomnia develop?

• Physiological predisposition — hyperactivity of the nervous system, a genetic predisposition for greater reactivity to stress.
• Precipitating factors Life events (grief, separation, job change), chronic pain, medical or psychiatric illnesses.
• Perpetuating factors — Inadequate sleep habits (caffeine at night, blue screens in bed), long naps, ruminative thoughts ("if I don't fall asleep I'll fail tomorrow"), compensatory behaviors (staying in bed watching series), which reinforce wakefulness.

Spielman's model (3 Ps) demonstrates how these components interact, justifying the multimodal approach to treatment.