Right, before you reach for the roller — most "dark, depressing room" problems are lighting problems, not paint problems. A single ceiling pendant blasting one cold beam straight down is what makes a room feel like a dentist's waiting area, and no colour on earth fixes that.
The trick is layering. You want three or four light sources at different heights working together: ceiling for general fill, a couple of table or floor lamps at eye level, and ideally something low — a small lamp on a shelf or a wall light. Lamps at lower levels bounce light off your walls and ceiling, which is exactly what makes a space feel warm and inhabited rather than flatly lit.
Get the bulbs right. For living rooms and bedrooms, stick to 2700K — that's proper warm white, the colour of old tungsten. Anything labelled 4000K or above ('cool white' / 'daylight') will make the room feel clinical and grey, and it'll murder warm paints especially. Then check the CRI (colour rendering index) — buy bulbs rated 90+ if you can. Cheap LEDs with a CRI in the low 80s render colour badly, so your lovely warm neutral looks muddy and lifeless. Decent CRI is the single most overlooked fix.
What about the walls themselves? You don't need to repaint, but if you ever do, a higher-LRV warm neutral reflects more of that lamplight back into the room. Things like Farrow & Ball Pointing, Farrow & Ball Skimming Stone or Little Greene Slaked Lime bounce light beautifully under warm bulbs. A satin or eggshell finish on woodwork also catches and reflects more light than a dead matt.
Mirrors help too — hang one opposite a window or near a lamp and you effectively double the light source.
Sort the lighting first, live with it a week, and I'd bet you won't touch the paint at all.