Bipolar

Symptoms of Bipolar

The core feature of bipolar disorder is a shift between high and low mood states, each lasting days to weeks at a time.

High mood (mania and hypomania) symptoms

High mood episodes can be severe (mania) or comparatively mild (hypomania).

  • Feeling unusually happy, euphoric, or excited
  • Feeling irritable or aggressive
  • High energy levels, restlessness, or a reduced need for sleep
  • Racing thoughts or difficulty concentrating
  • Rapid or pressured speech that can be difficult for others to follow
  • Increased libido
  • Overconfidence or a sense of grandiosity
  • Impulsive or reckless behaviour, such as excessive spending
  • Behaviour that is uncharacteristic, inappropriate, or out of keeping with usual judgement
  • In more severe cases, hallucinations, delusions, or paranoia

Low mood (depression) symptoms

  • Persistent sadness or low mood
  • Loss of interest or pleasure in usual activities
  • Low energy or persistent fatigue
  • Disturbed sleep – sleeping too much or too little
  • Changes in appetite – eating too much or too little
  • Low self-confidence
  • Feelings of worthlessness or hopelessness
  • Difficulty concentrating
  • Withdrawal from social contact
  • Suicidal thoughts or thoughts of self-harm

Other physical and behavioural symptoms

  • Marked changes in sleep patterns – disruption to the body’s internal clock is increasingly understood to be a core driver of mood episodes in bipolar disorder, rather than simply a symptom of them.Liu, Y., Zhu, L.Y., Xiao, Q., Zeng, H.M., Zhan, Y.X., Yang, R.H., Lin, F.Z., Liu, D.L., Zeng, X.X. and Chen, B.F. (2026) ‘Circadian rhythm disruption in bipolar disorder: mechanisms, clinical significance, and rhythm-oriented interventions’, World Journal of Psychiatry, 16(3), p.114301.
  • Changes in appetite and weight
  • Fluctuations in energy and activity levels
  • Changes in libido
  • Impaired concentration and decision-making

Different types of Bipolar disorder

Bipolar disorder is classified according to the pattern, severity, and duration of mood episodes.

Characterised by at least one manic episode lasting a week or more (or requiring hospitalisation), which may be preceded or followed by episodes of depression.

Characterised by at least one episode of major depression and at least one episode of hypomania, without a full manic episode. Bipolar II is frequently under-recognised and misdiagnosed as unipolar depression, as hypomanic episodes can be milder, briefer, and less disruptive than mania, and are often not recalled or reported by patients.Berk, M., Corrales, A., Trisno, R., Dodd, S., Yatham, L.N., Vieta, E., McIntyre, R.S., Suppes, T. and Agustini, B. (2025) ‘Bipolar II disorder: a state-of-the-art review’, World Psychiatry, 24(2), pp.175–189.

A milder, more chronic form involving numerous periods of hypomanic and depressive symptoms that do not meet the full criteria for hypomania or major depression, persisting for two years or more in adults.

A course specifier applied when a person experiences four or more mood episodes within a twelve-month period.

Episodes in which symptoms of mania and depression occur at the same time or in rapid succession, such as feeling agitated and energised while also feeling hopeless.

Some people experience hallucinations or delusions during severe manic or depressive episodes; these psychotic symptoms are usually thematically consistent with the prevailing mood (for example, grandiose delusions during mania, or delusions of guilt during depression). See our Psychosis page for more detail.

Diagnosing bipolar disorder

There is no single test that diagnoses bipolar disorder. Diagnosis is usually made by a psychiatrist or other mental health specialist, following referral from a GP, and is based on a detailed clinical history of mood, behaviour, sleep, and functioning over time, together with family history.

Because bipolar disorder can resemble other conditions – including unipolar depression, anxiety disorders, ADHD, and personality disorders – diagnosis can take time, and accurate diagnosis often depends on identifying a past episode of hypomania or mania that may not have been recognised as a mental health issue at the time. Diagnostic delay remains a significant and well-documented challenge in bipolar disorder, largely due to this overlap with unipolar depression.Oliva, V., Fico, G., De Prisco, M., Gonda, X., Rosa, A.R. and Vieta, E. (2025) ‘Bipolar disorders: an update on critical aspects’, The Lancet Regional Health – Europe, 48, p.101135.

Tools that may support diagnosis and monitoring include:

Tracking mood, sleep, and energy levels over time can help identify patterns and support an accurate diagnosis.

Structured or semi-structured interviews, anchored to DSM-5 or ICD-11 criteria, help distinguish bipolar disorder from other mood and psychiatric conditions.

Information from family members or close contacts can be valuable, since people experiencing hypomania or mania do not always recognise the episode as abnormal at the time.

Investigations and Tests

There is no blood test that diagnoses bipolar disorder. However, medical investigations are useful for ruling out other conditions that can cause mood symptoms, and for establishing a safe baseline before starting medication.

Used to check thyroid function, vitamin and mineral levels, kidney and liver function, and blood glucose, since abnormalities in any of these can contribute to or mimic mood symptoms, and are also relevant to the safe prescribing of mood-stabilising medication.

Checks for recreational drug use, which can trigger or worsen mood episodes.

Before starting certain mood stabilisers, tests such as kidney function, thyroid function, and, for some medications, an ECG are used to establish a safe baseline and guide ongoing monitoring.

In integrative and functional medicine, additional testing – such as inflammatory markers, nutritional panels, and assessment of circadian and sleep patterns – may also be used to help identify contributing factors. Research into biological markers of illness state, including mitochondrial function, is ongoing but not yet part of routine clinical diagnosis.Giménez-Palomo, A., Andreu, H., de Juan, O., Olivier, L., Ochandiano, I., Ilzarbe, L., Valentí, M., Stoppa, A., Llach, C.-D., Pacenza, G., Andreazza, A.C., Berk, M., Vieta, E. and Pacchiarotti, I. (2024) ‘Mitochondrial dysfunction as a biomarker of illness state in bipolar disorder: a critical review’, Brain Sciences, 14(12), p.1199.