Introduction: Bipolar disorder is characterized by recurrent episodes of depression and hypomania and is often associated with functional impairment even between mood episodes. A substantial proportion of patients experience inter-episode mood swings, making bipolar disorder a complex psychiatric disorder to manage. Patients’ perspectives can enhance clinical practice and research. The present study aimed to explore the impact of the bipolar disorder experience from a patient’s perspective to facilitate better understanding in clinical practice and future research. Method: We conducted a single case study with a key informant living with bipolar disorder (type I) for more than 20 years. The key informant constructed a chart of his mood disorder experiences. Subsequently, he commented on the chart and these comments were noted down by his therapist. Results: We present a chart of lived experience perception by a person living with bipolar disorder. The main axis was reality perception and it was related with mood, identity, and functioning. The comments on the chart provided a detailed and accurate description of a lived experience of functioning of bipolar disorder and its impact on a person’s life. Discussion: Globally, the experiences described by the key informant are consistent with previous literature. The principal finding was the meaning of the subjective experiences of reality perception, their relation with mood change, and impact on the person’s life. The perception of reality seems to be a key factor in the experience of bipolar mood swings. Not only did the disorder affect the self and the functioning, but at its extreme, reality “either did not matter or did not exist.” This feeling enhanced the sense of being disconnected from the world and the surroundings and led to the experience of extreme loneliness. Conclusion: The description in this study cannot be generalized, since it was conducted with only one subject. However, it provided a better insight into the detailed real-life experience that can be useful for clinicians treating persons living with bipolar disorder. Such descriptions obtained from a qualitative procedure can also be combined with quantitative data in patients' assessments and research. This study suggests that the experience of “disconnection” should be investigated further.