Sleep is something we do every day, yet we can’t simply decide to do it. We can create conditions that make sleep more likely, but the transition itself requires a peculiar kind of surrender: attention loosens, awareness of the outside world diminishes, and conscious control gradually gives way to processes that largely take care of themselves.

This can make persistent sleep difficulties particularly frustrating. The more important sleep becomes, the more closely people can monitor it. Someone who previously went to bed without much thought may begin calculating how many hours remain before morning, checking whether they feel sleepy enough, noticing every sound or bodily sensation, or predicting how badly they will function the following day.

Understandably, people then begin trying to solve the problem. They may go to bed earlier, stay in bed longer, cancel activities after a poor night’s sleep, sleep late when possible, nap during the day or develop increasingly elaborate routines intended to ensure that sleep occurs. Some of these strategies can be useful in particular circumstances. Others can unintentionally make sleep more fragile by increasing the amount of time and attention organised around it.

Sleep can also become associated with wakefulness itself. After enough nights spent awake, getting into bed may no longer signal rest. It can signal the place where I struggle to sleep. A person may feel tired throughout the evening only to become unexpectedly alert when they turn off the light. Concern about not sleeping then produces precisely the physiological and cognitive arousal that makes sleep less likely.

For other people, the difficulty is less about falling asleep than staying asleep. They may wake repeatedly, wake much earlier than intended, experience nightmares, or find that their mind becomes unusually active during the night. Thoughts that seemed manageable during the day can feel considerably larger at three in the morning when there are fewer competing demands on attention.

Sleep also exists within the broader rhythms of a person’s life. Work schedules, parenting, relationships, travel, light exposure, physical illness, medication, alcohol and other drugs, exercise, ageing and changes in routine can all influence when and how we sleep. Anxiety, depression, trauma and periods of prolonged stress can alter sleep as well, sometimes making it difficult to determine whether poor sleep is a cause, consequence or part of a mutually reinforcing cycle.

Not all sleep difficulties are primarily psychological. Conditions such as sleep apnoea, circadian rhythm disorders, restless legs syndrome and other medical or sleep disorders may require assessment by an appropriate health professional or sleep specialist. Understanding the problem therefore begins with understanding what kind of sleep difficulty this particular person is actually experiencing, rather than assuming that every poor sleeper has the same problem.