The best way to survive one is to avoid overnight bus travel all together. But if you really must, here are some tips to live by:
1. Never assume there will be a washroom on board. Carefully consider how much liquid you consumer prior to and during the trip.
2. Stock up on food. The bus will likely make a few stops but you’ll be at the mercy of whichever vendor the company has negotiated a stopover with. Usually they are large, cafeteria style restaurants with disappointing food options and a host of toilets around back, which you’ll have to pay to use. (Bring toilet paper!) It’s best just to order a takeaway sandwich or two for the road and hit a 7-11 for snacks.
3. Wear layers. Buses often run air conditioners overnight and it can get very cold. Make sure you bring a long sleeve shirt and consider packing a sleeping bag liner.
4. Essentials: Baby wipes and/or toilet paper, earplugs, and a flashlight if you intend to read.
5. Remember, you get what you pay for. 500 baht from Bangkok to Koh Samui may be tempting but consider spending a marginal amount more to travel with a reputable company.