Insomnia is a complaint of sleep being inadequate because it is too short (either after a long period of trying to get to sleep or due to early waking), too interrupted or not sufficiently restorative or refreshing resulting in impaired daytime function334.
The electrophysiological parameters of sleep can be assessed objectively using polysomnography (PSG), which monitors sleep architecture using electrodes applied to the scalp. However, insomnia is subjective and whilst objective data can be collected (e.g. time taken to get to sleep, duration of sleep, number of awakenings, etc.,), these data are often difficult to interpret and do not fully characterise the impact on the patient97.
However, there are more practical ways in which sleep can be assessed.
Assessing beliefs about normal sleep
There is no standard definition of what constitutes normal sleep61. While most healthy adults typically sleep between 7 and 9 hours per night, patterns vary greatly between people63. Some people may simply have a reduced need for sleep or an unrealistic expectation of sleep. If there is no impact on daytime functioning, the person does not have insomnia.
The time it takes to fall asleep is usually considered to be less than 30 minutes1478. However, sleep patterns are known to vary considerably with age; the number of awakenings increases and total sleep time decreases with a rise in age67.
Age-related trend for total nocturnal sleep time67
- Total sleep time
- 15 years
- 8 hours
- 20 years
- 7.5 hours
- 40 years
- 6.8 hours
- 60 years
- 6.3 hours
- 80 years
- 5.8 hours
Assessing the impact and duration of symptoms
As insomnia has a significant impact on a person's daytime functioning97 it is necessary to ask a patient about daytime functioning to establish the diagnosis. It is also important to assess the duration of symptoms as the management of short-term insomnia is different to that of long-term insomnia1.
- Short-term insomnia: lasts between 1 and 4 weeks
- Long-term (or persistent) insomnia: lasts for >4 weeks
(Note: the recently defined ‘insomnia disorder’ requires that sleep difficulty occurs at least 3 nights per week and is present for at least 3 months3.)
Assessing for secondary causes
Keeping a sleep diary
Sleep diaries can identify patterns, such as erratic schedules or predominant sleep patterns (for example, taking a long time to fall asleep, frequent awakenings), that are useful targets for behavioural treatments1623.
Using a structured questionnaire
The simplest way of assessing sleep is by asking the patient (and family member or carer where possible) about their sleep. Several screening questionnaires have been developed to assist health professionals eliminate other sleep disorders as the primary diagnosis11897.
Eliminating other sleep disorders as primary: preliminary questions197
- Do you have trouble falling asleep?
- Do you have trouble staying asleep?
- Do you wake up unrefreshed?
- Do you take anything to help you sleep?
- Do you use alcohol to help you sleep?
- Do you have any medical conditions that disrupt your sleep?
- Have you lost interest in hobbies or activities?
- Do you feel sad, irritable, or hopeless?
- Do you feel nervous or worried?
- Do you think something is wrong with your body?
Circadian rhythm disorder
- Are you a shift worker or is your sleep schedule irregular (i.e. do you tend to sleep well but just at the ‘wrong times’?)
Movement disorders (restless legs syndrome, periodic limb movements in sleep)
- Are your legs restless and/or uncomfortable before bed?
- Have you been told that you are restless or that you kick your legs in your sleep?
- Do you have any unusual behaviours or movements during sleep?
Sleep disordered breathing (sleep apnoea)
- Do you snore?
- Has anyone said that you stop breathing, gasp, snort, or choke in your sleep?
- Do you have difficulty staying awake during the day?
- Do you sometimes fall asleep in the daytime completely without warning?
- Do you have collapses or extreme muscle weakness triggered by emotion, for instance when you’re laughing?
It is important to determine if another sleep disorder (see preliminary questions above), or a physical (such as pain, heart or lung disease), neurological (such as Parkinson’s disease or cerebrovascular disease) or psychiatric disorder (such as depressive illness, anxiety disorder, or substance misuse) is concurrent with the insomnia. In many cases of depression, insomnia should be regarded as a co-morbid condition rather than a secondary one.
Referral to a sleep clinic or specialist
Referral to secondary care is recommended for someone with features of other sleep disorders where specialist training and experience may be required to establish the diagnosis and manage the condition1623.
- Major depressive episode
- Generalized anxiety or panic disorder
- Excessive daytime sleepiness (unexpected or irresistible sleepiness) resulting in imminent risk to the patient and/or society
- Substance abuse