Mania can be described as a state of abnormally elevated energy levels and general arousal. The typical symptoms of mania are the following: heightened mood (either euphoric or irritable), thought acceleration, a flooding of ideas, extreme talkativeness, increased energy, a decreased need for sleep, and hyperactivity.  This state of mind can vary wildly in its intensity, from mild mania (hypomania)  to full-on manic psychosis  . The accompanying symptoms are most obvious during states of fully developed delirious mania in which the person exhibits increasingly severe manic tendencies that become more and more obscured by other signs and symptoms, such as delusions, psychosis, incoherence, catatonia and extreme disorderly behaviour. 
Within the context of clinical psychology, standardized tools such as Altman Self-Rating Mania Scale  and Young Mania Rating Scale  can be used to measure the severity of manic episodes. It is worth noting that since mania and hypomania is often associated with creativity and artistic talent,  it is not always the case that a clearly manic person needs or wants medical help; such persons often either retain sufficient self-control to function normally or are simply unaware that they are severely manic enough to be committed to a psychiatric ward or to commit themselves.
Although mania is often stereotyped as a “mirror image” of depression, the heightened mood can be either euphoric or irritable. As irritable mania worsens, the irritability often becomes more pronounced and may eventually result in violent behaviour.
Mania is often accompanied by other coinciding effects such as ego inflation and stimulation. It is most commonly induced under the influence of heavy dosages of stimulant or dissociative compounds, such as methamphetamine, PCP, 2-Oxo-PCE, and cocaine.
Hypomania is a lowered state of mania that does little to impair function or decrease the person's quality of life.
It may, in fact, increase productivity and creativity. In hypomania, there is less need for sleep and an increase in both goal-motivated behaviour and physical metabolism. Though the elevated mood and energy levels typical of hypomania could be seen as a benefit, mania itself generally has many undesirable consequences including suicidal tendencies, and hypomania can, if the prominent mood is irritable rather than euphoric, be a rather unpleasant experience. By definition, hypomania cannot feature psychosis, nor does it require psychiatric hospitalisation (voluntary or involuntary).
When manic episodes are separated into stages of a progression according to symptomatic severity and associated features, hypomania constitutes the first stage of the syndrome, wherein the cardinal features (euphoria or heightened irritability, pressure of speech and activity, increased energy, decreased need for sleep, and flight of ideas) are most plainly evident.
- Manic Episode Symptoms (PsycheCentral) | https://psychcentral.com/disorders/manic-episode/
- Hypomanic episode symptoms (PSycheCentral) | https://psychcentral.com/disorders/hypomanic-episode-symptoms/
- Canuso, C. M., Bossie, C. A., Zhu, Y., Youssef, E., & Dunner, D. L. (2008). Psychotic symptoms in patients with bipolar mania. Journal of Affective Disorders, 111(2-3), 164-169. | https://doi.org/10.1016/j.jad.2008.02.014
- A comparative evaluation of three self-rating scales for acute mania (PubMed.gov / NCBI) | https://www.ncbi.nlm.nih.gov/pubmed/11566165
- A rating scale for mania: reliability, validity and sensitivity (PubMed.gov / NCBI) | https://www.ncbi.nlm.nih.gov/pubmed/728692
- Hypomania (APA) | http://dictionary.apa.org/hypomania
- Hypomania definition (alleydog) | https://www.alleydog.com/glossary/definition.php?term=Hypomania
- Hypomania (medicaldictionary) | https://medical-dictionary.thefreedictionary.com/hypomania