Why lie-ins can leave you feeling worse

There's a cruel irony in the weekend lie-in. You've earned it, you look forward to it all week, and yet by Sunday afternoon many of us feel foggy, sluggish and oddly unrefreshed. Monday arrives and you're somehow more tired than you were on Friday.

The culprit is something sleep researchers call social jet lag. Your body runs on an internal clock, roughly 24 hours long, that governs when you feel alert, when you feel sleepy, when your body temperature rises and falls, and when your digestive system expects food. That clock relies on consistency. When you shift your waking time by two or three hours on a Saturday, it's a bit like flying to a different time zone for the weekend and flying back again on Monday morning — without the holiday.

Every hour of drift between your weekday and weekend schedule adds to that effect. Two hours of drift is roughly the equivalent of a weekend break two time zones away. Three hours, and you've travelled further still. Your body can cope with the odd shift, but doing it week after week keeps your clock permanently unsettled.

How much drift is actually fine?

The good news is that you don't need to be rigid. A perfectly identical schedule seven days a week is unrealistic for most people, and the stress of chasing it can be worse than a small lie-in.

As a general rule, aim to keep your weekend wake time within 30 to 60 minutes of your weekday wake time. That's enough to feel like a treat without confusing your body clock. If you normally wake at 6.30am, a 7.15am start on Saturday is fine. A 9am start is where things begin to unravel.

Bedtime can be a little more flexible — your clock is anchored more strongly by when you wake and when you see morning light than by when you fall asleep. But keeping bedtime within about an hour of normal will make the whole weekend feel steadier.

Friday night: the first domino

Most people's weekend drift begins on Friday evening, not Saturday morning. The week is over, there's a film to watch, a book you've been meaning to finish, or simply the pleasure of being awake without obligation. Midnight slides to 1am without much resistance.

If you do stay up late on Friday, the key is not to let Saturday morning drift too far in response. Try setting an alarm for no more than an hour later than usual. It feels harsh at the time, but it protects the rest of your weekend — and it means Sunday night won't be a battle.

A few things that help on Friday evenings:

• Decide your Saturday wake time before you go out, and set the alarm for it.
• Keep the last hour before bed dim and low-key — lamps rather than overhead lights, screens on a warmer setting.
• If you're drinking alcohol, remember it fragments sleep in the second half of the night, so a late night plus drinks tends to produce a restless, shallow sleep rather than a deep one.

Saturday: the anchor that holds everything

Saturday morning is your best opportunity of the week to reset. The single most effective habit is getting outside within an hour of waking. Natural daylight is far brighter than indoor lighting, and it's the strongest signal your body clock receives. Even ten or fifteen minutes with a cup of tea in the garden, a walk to the shop, or a slow wander round the park helps.

If you're genuinely sleep-deprived from the week, nap rather than lie in. A nap of 20 to 30 minutes, ideally before 3pm, takes the edge off tiredness without pushing your body clock later. Longer naps, or naps in the early evening, tend to make it harder to fall asleep at a sensible hour.

Keep meals reasonably close to your weekday pattern too. Your digestive system has its own rhythms, and a very late Saturday dinner can leave you lying awake at midnight feeling uncomfortably full.

Sunday: protecting the landing

Sunday is where social jet lag does its damage. After two days of later mornings, an early Monday alarm feels brutal — and the anxiety about it can make Sunday night's sleep worse still.

Treat Sunday as a gentle return rather than a last chance to sleep. Wake at your usual weekend time, or even half an hour earlier. Get outside in the morning. Eat dinner at a normal hour. And if you feel the Sunday night dread creeping in, remind yourself that one restless night won't ruin your week — the goal is the pattern, not perfection.

If you can, keep Sunday evening calm and dim. A warm shower an hour or so before bed can help: the drop in body temperature afterwards is one of the natural signals that tells your brain it's time to sleep.

If your weekend has already gone sideways

Sometimes life wins. A wedding, a late flight, a baby who refuses to sleep — the schedule bends, and that's fine.

To get back on track, don't try to fix everything at once. Anchor the wake time first, even if it means a rough day. Get bright light early. Avoid caffeine after early afternoon, since it lingers in your system for hours. Go to bed at your normal time on Sunday even if you don't feel sleepy, and let your body find its rhythm again over two or three days.

Consistency doesn't have to be rigid. A weekend that stays within an hour of your weekday pattern, with a bit of morning daylight and a sensible bedtime, will give you far more energy than two long lie-ins ever could.