lethargy

https://doi.org/10.1351/goldbook.11848
Relatively mild impairment of consciousness resulting in reduced alertness and awareness.
Note: Lethargy has many causes but reflects a generalized suppression of brain activity.
Source:
PAC, 2015, 87, 841. (IUPAC Glossary of terms used in neurotoxicology (IUPAC Recommendations 2015)) on page 878 [Terms] [Paper]