There are many possible causes of insomnia, outlined below.
Stressful event
For some people, their insomnia starts in response to a stressful event and continues even when the stress has been resolved. This is because they have learnt to associate the sleeping environment with a state of being alert.
Causes of stress can be:
- situational - for example, worrying about work, money or health,
- environmental, such as noise, or
- death or illness of a loved one.
Psychiatric problem
Underlying mental health problems can affect your sleeping patterns, including:
- mood disorders, such as depression or bipolar disorder,
- anxiety disorders, such as generalised anxiety, panic disorder or post-traumatic stress disorder, and
- psychotic disorders, such as schizophrenia.
Physical condition
Insomnia can be caused by an underlying physical condition, including:
- heart disease, such as angina or heart failure,
- respiratory disease, such as chronic obstructive pulmonary disease or asthma,
- neurological disease, such as Alzheimer's or Parkinson's disease,
- hormone problems, such as an overactive thyroid,
- joint or muscle problems, such as fibromylagia or arthritis,
- gastrointestinal disease, such as gastro-oesophageal reflux disease or irritable bowel syndrome,
- problems with the genital or urinary organs, such as incontinence or an enlarged prostate,
- sleep disorders, such as restless legs syndrome, narcolepsy or sleep apnoea, and
- chronic (long-term) pain.
Drug and substance misuse
This includes the misuse of:
- alcohol,
- recreational drugs,
- caffeine, or
- nicotine.
Medication
Some prescribed or over-the-counter medicines can cause insomnia, including:
- antidepressants,
- epilepsy medicine,
- medication for high blood pressure, such as beta-blockers,
- hormone treatment,
- non-steroidal anti-inflammatory drugs (NSAIDs),
- stimulant drugs, such as methylphenidate to treat ADHD or modafinil to treat narcolepsy, and
- some medicines for asthma, such as salbutamol, salmeterol and theophylline.
