There's no airline-style weight limit, but space in the cabins is genuinely tight, so pack sensibly. As a rule of thumb, bring what you can manage yourself: a suitcase or holdall plus a smaller bag is fine, and there's room for cases under the lower berth or in the luggage areas at the end of each coach. Very large items, multiple big cases or anything you can't lift are best avoided, because cabins are compact and corridors are narrow. Keep an overnight bag with what you need for the night (toiletries, a change of clothes, phone charger) within reach so you're not opening a big case in a small space. Bicycles are carried separately by free reservation rather than as luggage, and there are restrictions on items like bike boxes and tandems. If you're travelling with unusually bulky luggage or sports equipment, it's worth checking with the operator before you travel. In short: normal holiday luggage is no problem, but the sleeper rewards packing light — a soft or medium case beats a giant hard-shell in a cabin every time.
Sources: sleeper.scot
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