Styles
Sleepwear
Body temperature drops, then rises before waking, and moisture is produced throughout. Sleepwear either handles that or interrupts it.
Core body temperature follows a daily rhythm: it falls in the hours around falling asleep and rises again towards morning. Skin temperature moves in the opposite direction at the start of the night, as blood flow to the extremities increases to shed heat. Moisture is produced continuously, more in some people than others. Sleepwear that traps that moisture against skin is the reason for waking up clammy at three in the morning.
What to look for
- A fibre that takes moisture into itself: cotton, modal, lyocell or silk. See cotton and modal.
- A loose cut. Sleepwear that grips restricts blood flow to the skin, which is the mechanism the body uses to regulate temperature at night.
- A soft, wide waistband, ideally a drawstring or a covered elastic, never a narrow exposed elastic that leaves a mark.
- Flat or bonded seams, particularly at the shoulder and the side, since lying on a raised seam for hours is a genuine cause of irritation.
- No hard trims. Buttons at the back of a waistband, decorative studs and stiff lace at a neckline are all things to be lain on.
The waistband is the single most important detail in sleepwear, and it is the detail nobody checks in a shop.
Fabric by season
| Fabric | Warmth | Moisture handling | Suits |
|---|---|---|---|
| Cotton jersey | Moderate | Absorbs, dries slowly | Most of the year |
| Cotton poplin | Low | Absorbs, breathes well | Warm nights |
| Modal or lyocell | Low to moderate | Absorbs, dries faster | Warm nights, sensitive skin |
| Silk | Adaptive | Absorbs, feels dry | Both extremes, at a cost in washing |
| Brushed cotton | High | Absorbs, slow | Cold rooms |
| Polyester satin | Low | Poor | Looks good, sleeps badly |
Polyester satin is the one to be sceptical about. It is smooth and hard wearing and it does not absorb moisture, so anything the body produces stays on the skin. For a warm sleeper it is the worst available option, whatever it looks like on a hanger.
Wearing a bra in bed
There is no evidence that sleeping in a bra causes harm, and none that it prevents anything either. It is a comfort question with a straightforward answer: if lying down without support is uncomfortable, wear something soft and unstructured. A wire in bed is a poor idea for the simple mechanical reason that a rigid arc pressing on tissue for eight hours while the body rolls over is exactly the situation wires handle worst.
A soft bralette one size up, with no wire and a wide soft band, is the sensible version. Anything that leaves a mark by morning is too tight for the job.
Nightwear and skin
Overnight is when most skin care is applied, and most of it ends up on the sleepwear. Anything oil based will migrate into fabric and will not fully wash out of silk at the temperatures silk tolerates, which is why a silk camisole and a rich body oil are a poor combination. Massage and body oils sold for skin, including those at inWonderstate, behave no differently: give them time to absorb, or wear cotton.
Detergent residue matters more in sleepwear than in day clothes, because it is against skin for eight uninterrupted hours. A second rinse is worth it for anyone whose skin reacts. Skin and friction covers this in more detail.
How often to wash it
More often than most people do. Sleepwear collects skin cells, sebum and whatever was applied at bedtime, and it does so for a longer continuous period than almost any other garment. Once or twice a week for pyjamas in ordinary conditions, more in warm weather or for a warm sleeper. Cotton tolerates 40 degrees comfortably; silk and any elastane blend do not, and belong in the routine set out in hand washing.